True Televisions have the CRT Tube !!
Welcome to the Obsolete Technology Tellye Web Museum. Here you will see a TV Museum showing many Old Tube Television sets
all with the CRT Tube, B/W ,color, Digital, and 100HZ Scan rate, Tubes technology. This is the opportunity on the WEB to see, one more time, what real technology WAS ! In the mean time watch some crappy lcd picture around shop centers (but don't buy them, or money lost, they're already broken when new) !!!

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and information about some of the electronic, electrical and electrotechnical technology relics that the Frank Sharp Private museum has accumulated over the years .

Premise: There are lots of vintage electrical and electronic items that have not survived well or even completely disappeared and forgotten.

Or are not being collected nowadays in proportion to their significance or prevalence in their heyday, this is bad and the main part of the death land. The heavy, ugly sarcophagus; models with few endearing qualities, devices that have some over-riding disadvantage to ownership such as heavy weight,toxicity or inflated value when dismantled, tend to be under-represented by all but the most comprehensive collections and museums. They get relegated to the bottom of the wants list, derided as 'more trouble than they are worth', or just forgotten entirely. As a result, I started to notice gaps in the current representation of the history of electronic and electrical technology to the interested member of the public.

Following this idea around a bit, convinced me that a collection of the peculiar alone could not hope to survive on its own merits, but a museum that gave equal display space to the popular and the unpopular, would bring things to the attention of the average person that he has previously passed by or been shielded from. It's a matter of culture. From this, the Obsolete Technology Tellye Web Museum concept developed and all my other things too. It's an open platform for all electrical Electronic TV technology to have its few, but NOT last, moments of fame in a working, hand-on environment. We'll never own Colossus or Faraday's first transformer, but I can show things that you can't see at the Science Museum, and let you play with things that the Smithsonian can't allow people to touch, because my remit is different.

There was a society once that was the polar opposite of our disposable, junk society. A whole nation was built on the idea of placing quality before quantity in all things. The goal was not “more and newer,” but “better and higher" .This attitude was reflected not only in the manufacturing of material goods, but also in the realms of art and architecture, as well as in the social fabric of everyday life. The goal was for each new cohort of children to stand on a higher level than the preceding cohort: they were to be healthier, stronger, more intelligent, and more vibrant in every way.

The society that prioritized human, social and material quality is a Winner. Truly, it is the high point of all Western civilization. Consequently, its defeat meant the defeat of civilization itself.

Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

OLD, but ORIGINAL, Well made, Funny, Not remotely controlled............. and not Made in CHINA.

How to use the site:

- If you landed here via any Search Engine, you will get what you searched for and you can search more using the search this blog feature provided by Google. You can visit more posts scrolling the left blog archive of all posts of the month/year,or you can click on the main photo-page to start from the main page. Doing so it starts from the most recent post to the older post simple clicking on the Older Post button on the bottom of each page after reading , post after post.

You can even visit all posts, time to time, when reaching the bottom end of each page and click on the Older Post button.

- If you arrived here at the main page via bookmark you can visit all the site scrolling the left blog archive of all posts of the month/year pointing were you want , or more simple You can even visit all blog posts, from newer to older, clicking at the end of each bottom page on the Older Post button.So you can see all the blog/site content surfing all pages in it.

- The search this blog feature provided by Google is a real search engine. If you're pointing particular things it will search IT for you; or you can place a brand name in the search query at your choice and visit all results page by page. It's useful since the content of the site is very large.

Note that if you don't find what you searched for, try it after a period of time; the site is a never ending job !

Every CRT Television saved let revive knowledge, thoughts, moments of the past life which will never return again.........

Many contemporary "televisions" (more correctly named as displays) would not have this level of staying power, many would ware out or require major services within just five years or less and of course, there is that perennial bug bear of planned obsolescence where components are deliberately designed to fail and, or manufactured with limited edition specificities..... and without considering........picture......sound........quality........

Saturday, September 17, 2011

Note the convergence assy on the deflection joke assy and the beam SVM (scan velocity modulation) unit on the neck of the tube and the H-STAT Regulator on the HV side.

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Trinitron is Sony's brand name for its line of aperture grille based CRTs used in televisions and computer monitors. One of the first truly new television systems to enter the market since the 1950s, the Trinitron was announced in 1966 to wide acclaim for its bright images, about 25% brighter than common shadow mask televisions of the same era. Constant improvement in the basic technology and attention to overall quality allowed Sony to charge a premium for Trinitron devices into the 1990s.
Patent protection on the basic Trinitron design ran out in 1996, and it quickly faced a number of competitors at much lower price points. Sony responded by introducing their flat-screen FD Trinitron designs (WEGA), which maintained their premier position in the market into the early 2000s. However, these designs were surpassed relatively quickly by plasma and LCD designs. Sony removed the last Trinitron televisions from their product catalogs in 2006, and ceased production in early 2008. Video monitors are the only remaining Trinitron products being produced by Sony, at a low production rate, although the basic technology can still be found in downmarket televisions from 3rd parties.
The name Trinitron was derived from trinity, meaning the union of three, and tron from electron tube, after the way that the Trinitron combined the three separate electron guns of other CRT designs into one.

Trinitron

In the autumn of 1966 Ibuka finally gave in, and announced he would personally lead a search for a replacement for Chromatron. Susumu Yoshida was sent to the U.S. to look for potential licenses, and was impressed with the improvements that RCA had made in overall brightness by introducing new rare earth phosphors on the screen. He also saw General Electric's "Porta-color" design, using three guns in a row instead of a triangle, which allowed a greater portion of the screen to be lit. His report was cause for concern in Japan, where it seemed Sony was falling ever-farther behind the U.S. designs. They might be forced to license the shadow mask system if they wanted to remain competitive.[10]
Ibuka was not willing to give up entirely, and had his 30 engineers explore a wide variety of approaches to see if they could come up with their own design. At one point Yoshida asked Senri Miyaoka if the in-line gun arrangement used by GE could be replaced by a single tube with three cathodes; this would be more difficult to build, but be lower cost in the long run. Miyaoka built a prototype and was astonished how well it worked, although it had focussing problems.[10] Later that week, on Saturday, Miyaoka was summoned to Ibuka's office while he was attempting to leave work to attend his weekly cello practice. Yoshida had just informed Ibuka about his success, and the two asked Miyaoka if they could really develop the gun into a workable product. Miyaoka, anxious to leave, answered yes, excused himself, and left. That Monday Ibuka announced that Sony would be developing a new color television design, based on Miyaoka's prototype.[11] By February 1967 the focusing problems had been solved, and because there was a single gun, the focusing was achieved with permanent magnets instead of a coil, and required no after manufacturing manual adjustments.
During development, Sony engineer Akio Ohgoshi introduced another modification. GE's system improved on the RCA shadow mask by replacing the small round holes with slightly larger rectangles. Since the guns were in-line, they would shine onto the back of the tube onto three rectangular patches instead of three smaller spots, about doubling the lit area. Ohgoshi proposed removing the mask entirely and replacing it with a series of vertical slots instead, lighting the entire screen. Although this would require the guns to be very carefully aligned with the phosphors on the tube in order to ensure they hit the right colors, with Miyaoka's new tube this appeared possible.[11] In practice this proved easy to build but difficult to place in the tube – the fine wires were mechanically weak and tended to move when the tubes were bumped, resulting in shifting colors on the screen. This problem was solved by running fine tungsten wires across the grille horizontally to keep them in place.
The combination of three-in-one electron gun and the replacement of the shadow mask with the aperture grille resulted in a unique and easily patentable product. Officially introduced by Ikuba in April 1968, the original 12 inch Trinitron had a display quality that easily surpassed any commercial set in terms of brightness, color fidelity, and simplicity of operation. The tube was also flat vertically, a side-effect of the vertical wires in the aperture grille, which gave it a unique and appealing look. It was also all solid state, with the exception of the picture tube itself, which allowed it to be much more compact and cool running than designs like GE's Porta-color.
Ikuba ended the press conference by claiming that 10,000 sets would be available by October, well beyond what engineering had told him was possible. Ikuba cajoled Yoshida to take over the effort of bringing the sets into production, and although Yoshida was furious at being put in charge of a task he felt was impossible, he finally accepted the assignment and successfully met the production goal.[12] The KV-1310 was introduced in limited numbers in Japan in October as promised, and in the U.S. as the KV-1310U the following year.
In spite of Trinitron and Chromatron having no technology in common, the shared single electron gun has led to many erroneous claims that the two are similar, or the same.[13]
Despite the statement above claiming that there were no valves inside Trinitron TV sets, for a brief period in the United Kingdom between 1969 and 1971/72, the KV-1320UB was fitted with 3AT2 valves for the extra high tension. Later on, the KV-1320UB was redesigned internally and externally to become all solid-state. Despite containing vacuum tubes, the first version of the KV-1320UB was promoted as being all solid-state. The later version of this model is identified as having no wooden outer-shell. These early color sets intended for the UK market had a PAL decoder that was different from those invented and licensed by Telefunken of Germany, who invented this color system. The decoder inside the UK-sold Sony color Trinitron sets, from the KV-1300UB to the KV-1330UB had an NTSC decoder adapted for PAL. The decoder used a 64 microsecond delay line to store every other line, but instead of using the delay line to average out the phase of the current line and the "remembered" line (as with "Deluxe PAL"), it simply repeats the same line twice. Any phase errors can then be compensated for by using a Tint control on the front of the set.

Close-up of phosphor bars on a 14" Sony Trinitron television.

Basic concept
The Trinitron design incorporates two unique features: the single-gun three-cathode picture tube, and the vertically aligned aperture grille.
The single-gun consists of a long-necked tube with a single electrode at its base, flaring out into a horizontally-aligned rectangular shape with three vertically-aligned rectangular cathodes inside. Each cathode is fed the amplified signal from one of the decoded RGB signals.
The electrons from the cathodes are all aimed toward a single point at the back of the screen where they hit the aperture grille, a steel sheet with vertical slots cut in it. Due to the slight separation of the cathodes at the back of the tube, the three beams approach the grille at slightly different angles. When they pass through the grille they retain this angle, hitting their individual colored phosphors that are painted in vertical stripes on the inside of the tube. The main purpose of the grille is to ensure the beams are properly registered with the phosphors.

Advantages

In comparison to early shadow mask designs, the Trinitron grille cuts off much less of the signal coming from the electron guns. RCA sets built in the 1950s cut off about 85% of the incoming signal, while the grille cuts off about 25%. Improvements to the shadow mask designs continually narrowed this difference in the two designs, and by the late 1980s the difference in performance, at least theoretically, was eliminated.
Another advantage of the aperture grille was that the distance between the wires remained constant vertically across the screen. In the shadow mask design the size of the holes in the mask is defined by the required resolution of the phosphor dots on the screen, which was constant. However, the distance from the guns to the holes changed; for dots near the center of the screen the distance was its shortest, at points in the corners it was at its maximum. To ensure that the guns were focused on the holes, a system known as dynamic convergence had to constantly adjust the focus point as the beam moved across the screen. In the Trinitron design the problem was greatly simplified, requiring changes only for large screen sizes, and only on a line-by-line basis.
For this reason, Trinitron systems are easier to focus than shadow masks, and generally had a sharper image. This was a major selling point of the Trinitron design for much of its history. In the 1990s new computer controlled real-time feedback focusing systems eliminated this advantage, as well as leading to the introduction of "true flat" designs.

Visible Support Wires

Even small changes in the alignment of the grille over the phosphors can cause the coloring to shift. Since the wires are thin, small bumps can cause the wires to shift alignment if they are not held in place. Monitors using this technology have one or more thin tungsten wires running horizontally across the grille to prevent this. Screens 15" and below have one wire located about two thirds of the way down the screen, while monitors greater than 15" have 2 wires at the one-third and two-thirds positions. These wires are less apparent or completely obscured on standard definition sets due to larger scan lines of the video being displayed. On computer monitors, where the lines are much closer together, the wires are often visible. This is a minor drawback of the Trinitron standard which is not shared by shadow mask CRTs.

GRID STRUCTURE FOR SONY TRINTRON COLOR PICTURE TUBES:

A support for the grid structure of a cathode-ray tube in which the support is stressed to compensate for any expansion of the grid wires due to heating, the support having a pair of opposed parallel arms with the grid wires attached to and extending transversely between the arms, and a pair of braces supporting the arms at the Bessel points, the braces being stressed in a direction substantially parallel to the direction of the grid wires so that as the grid wires expand due to heat the braces will expand a

corresponding amount to maintain a substantially constant tension of the grid wires.1. A support for the grid elements of a cathode ray tube comprising a pair of opposed parallel arms, a plurality of said grid elements affixed to said arms and extending transversely therebetween, a pair of generally C-shaped braces supporting said arms and attached thereto substantially at the Bessel points and formed to lie in surfaces substantially parallel to the surface defined by said grid elements, said braces being stressed a sufficient amount in a direction substantially parallel to the direction of said grid elements whereby as said grid elements expand said braces expand a corresponding amount to maintain the tension on all of said grid elements substantially uniform.

2. A support for a grid structure of a cathode ray tube comprising a pair of opposed parallel arms, a plurality of flexible grid wires affixed to said arms and extending therebetween, a pair of mechanically resilient braces supporting said arms and attached thereto at locations inwardly spaced from the ends of said arms substantially at the Bessel points, and said braces being stressed in a direction substantially parallel to the direction of said flexible grid wires to apply tension stress to said grid wires whereby as said flexible grid wires expand due to heat generated during the operation of the tube, said braces expand due to their resiliency and their being stressed a corresponding amount to maintain the tension on all of said flexible grid wires substantially uniform.

3. A support in accordance with claim 2 wherein said braces are substantially C-shaped.

4. A support in accordance with claim 2 wherein a damping rod extends over said flexible members to substantially eliminate mechanical vibration of said flexible members.

5. A support in accordance with claim 4 wherein said damping rod is stretched between said braces.

6. A support in accordance with claim 5 wherein said damping rod is flexible and is attached substantially to the center of said braces.

7. A support according to claim 6 wherein the damping rod is inclined relative to flexible grid wires.

8. A support in accordance with claim 6 wherein said damping rod resiliently presses against said flexible members.

9. A support according to claim 8 wherein said damping rod has a diameter of between 30 and 50 microns.

Description:

This invention relates to a novel grid structure for color picture tubes, and more particularly to a grid structure which is of particular utility when employed in color picture tubes.

As is well known in the prior art, color cathode ray tubes employ, for electron beam postdeflection and focusing, a grid structure such that a plurality of parallel grid wires are stretched across a parallelogramic frame between a pair of opposed sides. Such a grid structure is produced in the following manner. A plurality of parallel grid wires are stretched on a master frame under predetermined taut conditions and a grid frame is put on the grid wires from inside of the master frame. The grid wires are then fixed to a pair of opposed supports of the grid frame and are thereafter severed along the margins of the grid frame. In this case, the grid frame is prestressed inwardly by a turnbuckle to apply a maximum tension to the grid wires secured to the central portion of the opposed supports of the grid frame and a smaller tension to those fixed to end portions of the supports, ensuring that all the grid wires are subjected to substantially uniform tension by the restoring force of the prestressed grid frame after disassembling it from the master frame.

Such a grid structure may be regarded as one where a plurality of grid wires are stretched at substantially uniform tension on a parallelogramic frame prestressed in a manner to be displaced the most at the center of the frame. When a predetermined positive potential is applied to such a grid structure and electron beams are emitted from the electron gun of a cathode ray tube toward the fluorescent screen thereof, electron beams of several to 10-odd percent strike against the grid wires and are discharged therethrough to thereby heat the grid wires. As a result of this, the temperature of the grid wires is raised several-10 degrees and the wires expand. An examination of the expanded grid wires shows that since the displacement of the frame is greatest at the center thereof, elongation of the grid wires of that portion due to thermal expansion is cancelled by the restoring force of the prestressed frame as if the grid wires had not been elongated. Accordingly, the grid wires are still subjected to substantially the same original tension, and hence do not sag. The elongation of the grid wires lying on both sides of the central grid wires cannot be absorbed with the displacement of the frame at those particular portions, since the displacement is basically small. Consequently, when the elongation of the grid wires exceeds the displacement of the frame, the grid wires are likely to sag. Even if the grid wires do not sag, they are not pulled at a predetermined tension and are readily vibrated at great amplitude to lower the picture quality of the reproduced picture when subjected to accidental small shocks.

The above can easily be understood from the fact that when all the grid wires have substantially the same length 1, their elongation resulting from thermal expansion is 1 and the amount of restoration of the distorted frame is 1 at the center thereof, the amount of restoration of the frame on both sides of the center thereof is smaller than that at the central portion.

This defect is remarkable especially in the grid structure of a color cathode ray tube of the type where a plurality of ribbonlike grid elements are stretched in parallel with phosphor strips and function as a kind of shadow mask. In this type of structure three electron beams are impinged upon three different color emissive phosphor strips through slits defined between adjacent grid elements.
A grid structure such as described above has been proposed in an attempt to increase the electron beam transmission factor of the so-called shadow mask in which a plate having bored therethrough a plurality of apertures is used as a mask for the electron beam. In such a grid structure, however, the grid elements are secured only at both ends to the frame, so that the grid elements heated by electron beams striking thereon radiate heat mainly through the ends fixed to the frame. Further, the transmission factor of the electron beam through such a grid is 10-odd to 20-odd percent and the temperature of the grid elements rises up to 100° to 130° C. Consequently this type of grid structure encounters the same problems as in the Chromatron (Registered Trademark) type color cathode ray tube.

In addition to the sag of the grid elements, nonuniformity in the tension applied to the grid elements raises another problem in such a grid structure as mentioned above. Even slight nonuniformity in the tension causes the grid elements to twist and the space between adjacent grid elements becomes wider in a direction normal to the incident direction of the electron beam, although the pitch of the grid elements remains unchanged. As a result of this, there is the possibility that the electron beam strikes on a phosphor strip other than a predetermined one, especially a phosphor strip adjacent the predetermined one to cause unnecessary color emission. Therefore, the nonuniformity in the tension applied to the grid elements should be avoided.

Accordingly, one object of this invention is to provide a grid structure which is adapted such that the grid elements are always subjected to a predetermined tension and do not sag during operation, though heated by electron beams.

Another object of this invention is to provide a grid structure for shadow-mask type color cathode ray tubes in which the grid elements heated by electron beams do no sag during operation to thereby ensure uniformity in the spacing between adjacent grid elements and hence prevent unnecessary bombardment of the phosphor strips by the electron beam.

Still another object of this invention is to provide a grid structure which is constructed such that the grid elements are protected from shocks applied from the outside and caused by electron beam bombardment.

Other objects, features and advantages of this invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGS. 1 and 2 are schematic diagrams for explaining the present invention;

FIG. 3 is a plan view showing one example of a grid structure for color cathode ray tubes produced according to this invention;

FIG. 4 is a side view of the grid structure illustrated in FIG. 3;

FIG. 5 is a plan view illustrating another example of the grid structure of this invention;

FIG. 6 is a schematic diagram showing the manner in which the grid elements are mounted on a grid frame;

FIG. 7 is a plan view showing another modified form of the present invention;

FIG. 8 is a cross-sectional view taken along the line A--A in FIG. 7;

FIG. 9 illustrates in perspective the plate supports employed in the example of FIG. 7;

FIG. 10 similarly shows in perspective a resilient support;

FIG. 11 is a plan view showing still another modification of the present invention;

FIG. 12 is a side view of the grid structure depicted in FIG. 11; and

FIG. 13 is a perspective view of the grid structure shown in FIG. 11.

FIG. 1 is a schematic diagram showing displacement (indicated by broken lines) of a bar 1 of a length L having two fulcra 2A and 2B when subjected to a uniformly distributed load 3 acting substantially perpendicular to the bar. In order to minimize the displacement of the bar 1, the fulcra 2A and 2B are located at such positions that the displacement δ 1 of both end portions of the bar 1 is equal to the displacement δ 2 of the central portion. Such positions of the fulcra are referred to as the Bessel points, and when the distance from the end of the bar 1 to the fulcrum 2A or 2B is taken as b, b/L=0.223. The length L of the bar does not indicate the actual length but a range over which the load 3 is applied.

If a pair of such bars are arranged in parallel relation as a pair of opposed frame members of a grid frame, a plurality of grid wires or elements stretched between the frame members at substantially uniform tension are subjected to the aforementioned uniformly distributed load 3. In other words, where a pair of bars 1 and 1' (not shown) of a length L constituting two frame members are arranged in parallel relation and a plurality of parallel grid wires or elements are stretched between the bars substantially at right angles thereto under approximately uniformly tensioned conditions and fulcra 2A, 2B and 2A', 2B' (not shown) respectively supporting the bars are located at positions satisfying the aforementioned requirement b/L=0.223, the bars are deformed to be bent at both ends and between the fulcra by the load caused by the tension of the grid wires or elements in a direction of the tension but the displacement ratio, that is, the displacement per unit load is at minimum. Consequently, the displacement ratio of the frame of this invention (indicated by the broken line B in FIG. 2) is far smaller than that of the conventional grid frame (indicated by the full line A in FIG. 2) of the type where the fulcra are located at both ends of two bars constituting the frame members, and accordingly the grid frame of this invention virtually deformed as compared with the deformation of the conventional grid frame. If the rigidity of the bar 1 is increased up to maximum, the deformation of the frame can be neglected.

The tension of the grid wires or elements stretched between the two bars 1 and 1' (not shown) corresponding to the load 3 shown in FIG. 1 is produced by pressing the two bars with a resilient support (not shown) in a direction opposite to the load 3 in a manner to force away the two fulcra 2A and 2A' (2A' not shown) and 2B and (2B' not shown) from each other.

Referring now to FIGS. 3 to 10, the construction of the grid structure of this invention will be described in detail by way of example.

As clearly shown in the figures, the grid structure of this invention comprises a frame of a predetermined configuration which consists of bar supports 4 and 4' corresponding to the aforementioned bars 1 and 1' and a pair of substantially C-shaped resilient supports 5 and 5' supporting the bar supports 4 and 4' at or in the vicinity of the Bessel points B A , B B and B A ', B B ' thereof, and a plurality of ribbon-shaped grid elements of, for example, stainless steel are stretched between the bar supports 4 and 4' at a predetermined pitch under predetermined distribution of tension. Reference numeral 7 indicates generally the grid structure.

The bar supports 4 and 4' may be formed of a metal such as iron, stainless steel or the like and in the illustrated example the bar supports 4 and 4' are square in cross section and are bent to conform to the panel to which the grid structure will be attached. The resilient supports 5 and 5' may be formed of a metal such as iron, stainless steel or the like and are substantially C-shaped so as not to disturb the irradiation of the phosphor screen by the electron beam emitted from the electron gun of a cathode ray tube. It is a matter of course that the supports 5 and 5' may be configured at will so long as they do not disturb the electron beam directed to the fluorescent screen of the cathode ray tube. The grid elements 6 may also be formed of a metal such as iron, stainless steel or the like.

With such an arrangement, since the pair of bar supports 4 and 4' constituting one portion of the frame are jointed to the resilient supports 5 and 5' as a unitary structure at or in the vicinity of the Bessel joints B A , B B and B A ', and B B ', the bar supports 4 and 4' may be regarded as a rigid body with respect to the load caused by the tension of the grid elements. Accordingly, when the grid elements 6 that are stretched between the bar supports 4 and 4' uniformly at a predetermined tension expand by heat resulting from the electron beam bombardment thereon, the bar supports 4 and 4' are pulled outwards by the resilient supports 5 and 5' in a parallel relationship by a distance corresponding to the length of the grid elements which have been extended by the thermal expansion. Consequently, although the absolute value of the tension is different from the initial one, the initial distribution of the tension over the entire grid elements remains unchanged.

The foregoing description has been made in connection with a grid structure in which the grid elements are of substantially the same length at the both end portions and central portion of the bar supports and hence they are expanded substantially equally due to thermal expansion. According to our experiments on a grid structure in which the bar supports of square cross section were made of stainless steel and had a size of about 10 mm. × 10 mm. × 240 mm. and 400 grid elements 0.5 mm. wide, 0.1 mm. thick and about 180 mm. long (the length of the grid elements on the end portions of the bar supports were 175 mm. and that of the elements of the central portion: 185 mm.) were stretched between the bar supports at a tension of about 350 g. for each grid element, it has been ascertained that although the grid elements were heated by electron beams and extended due to thermal expansion during operation, accidents such as vibration of the grid elements due to nonuniformity of the tension or color contamination due to irregularity of the space between adjacent grid elements were not caused. Further, it has been found that the deviation from the initial distribution of the tension of the grid elements caused by the thermal expansion thereof resulting from the collision of the electron beam therewith were compensated for by the stretch or shrinkage of the grid elements or slight restoring force of the bar supports.

In addition, it has also been found that if the deviation of the length of the grid elements is in a range of ±20 percent relative to its mean value, the length of the grid elements extended by the thermal expansion is extremely short and the initial distribution of the tension of the grid elements is maintained during operation by the stretch and shrinkage of the grid elements or by compensation due to the restoring force of the bar supports.

In the prior art a very complicated device is required for stretching grid elements on a grid frame, but this can be readily achieved by the following method. As shown in FIG. 5, for example, a thin stainless steel plate 8 of a predetermined size is first prepared and is subjected to etching to remove selected areas, thus providing metal strips 8a arranged at a predetermined pitch. At the same time, slits 8b are formed for a predetermined number of metal strips 8a (every three metal strips in the figure) in the plate 8 at both marginal portions thereof. In a similar manner, slits 8c are formed in the plate 8 on both sides of the metal strips 8a. Portions 8d separated by the slits 8b are then respectively held by chucks 9A and 9B as shown in FIG. 6. In this case, the number of the chucks 9A and 9B corresponds to that of the portions 8d. The chucks 9B are supplied with a moderate tension in accordance with the thickness and the quality of material of the portions 8d, but such tension may be applied to both of the chucks 9A and 9B. Substantially the same tension is applied to the metal strips by means of, for example, a coiled spring 10 as shown in the figure. Under such taut conditions, a pair of bar supports 11 and 11' are disposed under the plate 8 at predetermined positions and the plate 8 is welded to the bar supports. In this case, the bar supports 11 and 11' are supported by a pair of resilient supports at or in the vicinity of their Bessel points, though not shown, and the resilient supports are slightly bent inwardly so as to apply a predetermined tension to the metal strips when the portions 8d are released from the chucks 9A and 9B. It is preferred that the force for bending the two resilient supports be equal to the tension (the total tension of all the metal strips) applied to the metal strips 8a by the spring 10. In such a case when the chucks 9A and 9B are removed, the tension of the metal strips 8a due to the spring 10 is applied to the strips 8a by the resilient supports, so that the tension of the metal strips 8a remains unchanged before and after the removal of the chucks.

Subsequent to the welding of the plate 8, the portions 8d projecting outside of the bar supports 11 and 11' are cut off and both end portions of the slits 8c are also cut off. The slits 8c are provided for facilitating the cutting of the plate 8, and hence they are not always necessary. In the manner described above, the metal strips 8a can readily be stretched between the bar supports 11 and 11' with predetermined distribution of the tension. In this case, the metal strips 8a are coupled together at both ends. It is possible, of course, that the end portions of the metal strips 8a are welded to the bar supports 11 and 11'. The slits 8b are provided for preventing the plate 8 from becoming creased when applying a tension to the edges of the plate 8 and for ensuring uniformity of the tension applied to each metal strip 8a. In the absence of the slits 8b, it is extremely difficult to apply the tension to the metal strips 8a with the predetermined distribution.

While the metal strips 8a are subjected to substantially equal tension by the chucks 9A and 9B in the above example, the distribution of the tension may be changed as desired in accordance with the shapes of the bar supports and the resilient supports and the condition of the resilient supports welded to the bar supports in the vicinity of the Bessel points thereof to ensure uniformity of the tension applied to the metal strips by the resilient supports.

The electron beam transmission factor depends upon the width of the metal strips or the diameter and the pitch of the metal wires, which are usually selected to render the electron beam transmission factor approximately 20 percent in view of the relationship to the width of each phosphor strip of the fluorescent screen of cathode ray tubes.

In FIGS. 7 and 8 there is illustrated another example of this invention, in which reference numeral 15 designates generally a grid structure. A pair of plate supports 12 and 12' are supported by a framelike resilient support 13 at or in the vicinity of their Bessel points to provide a frame of a predetermined configuration, and grid elements 14 in the form of, for example, metal strips are stretched between the pair of platelike supports 12 and 12'.

The plate supports 12 and 12' may be formed of a metal such as iron, stainless steel or the like and, as shown in FIG. 9, one marginal edge of each plate support is curved so as to conform to the surface of the panel of a cathode ray tube with which the finished grid structure will be assembled. The resilient support 13 may also be formed of a metal such as iron, stainless steel or the like and this support 13 has projections 13a at places substantially corresponding to the Bessel points of the plate supports 12 and 12' as illustrated in FIG. 10. Further, the support 13 has L-shaped plate support-retaining members 13b formed integrally at places corresponding to the projections 13a.

The pair of plate supports 12 and 12' are mounted on the retaining members 13b of the resilient support 13 in such a manner that the projections 13a of the support 13 engage the plate supports 12 and 12' at or in the vicinity of their Bessel points, and the plate supports and the resilient supports are held together by predetermined jigs in a manner to produce a predetermined pressure at or in the vicinity of the Bessel points of the plate supports 12 and 12' by the projections 13a of the resilient support 13. Then, the grid elements 14 are stretched between the pair of plate supports 12 and 12' at a predetermined distribution of tension.

With such an arrangement, the pair of plate supports 12 and 12' are supported by the projections 13a of the resilient support 13 at or in the vicinity of their Bessel points, so that the equilibrium of the tension is very stable after the grid elements 14 have once been stretched at the predetermined distribution of the tension. Accordingly, the equilibrium of the tension is not lost by a slight variation in the tension after stretching the grid elements 14 and the grid frame is not deformed. Further, the equilibrium of the tension is difficult to loose by thermal expansion of the frame or the grid elements 14 due to a temperature rise during operation, and even if the equilibrium of the tension is lost, the tension promptly balances, so that deformation of the frame is very slight. Consequently, the position of the grid elements 14 is not shifted and the electron beam always impinges upon the fluorescent screen accurately at a predetermined location, so that phenomenon such as color contamination is not caused thereby ensuring reproduction of a clear picture. In addition, since the grid structure described above is simple in construction, its fabrication is easy and the yield is greatly increased. Even if the grid elements 14 are stretched between the plate supports 12 and 12' at substantially uniform tension, the deformation of the frame is very slight as indicated by the dotted line B in FIG. 2. Accordingly, there is no possibility that the position of the grid elements 14 is shifted by a slight deformation of the frame and by thermal expansion of the grid elements or the frame due to a temperature rise. That is, even if the grid elements 14 are stretched at uniform tension, the aforementioned many advantages can still be obtained.

The assembling of the grid structure with the panel of a cathode ray tube can readily be achieved by the same means as mentioned previously or by other known means, and accordingly no description will be given. Further, it is needless to say that the aforementioned method can be used for stretching the grid elements, and the metal wires may be stretched as the grid elements 14 at a predetermined pitch in place of the metal strips.

The foregoing description has been made in connection with only several examples of this invention, and the material, shape and the like of the bar supports, plate supports, grid elements, resilient supports and so on can be suitably selected at will, if necessary. However, the bar supports and the plate supports are desired to be formed of a conductive material so as to establish electric fields between the supports and the grid elements. Further, these supports are not restricted to the bar and plate supports.

When the grid structure is used in color picture tubes the grid elements are caused to vibrate by mechanical vibration due to external shocks or electron beam bombardment. In FIGS. 11 to 13 there is shown still another example of this invention in which the grid structure is designed to prevent such unwanted vibration of the grid elements.

In the figures reference numerals 21A and 21B indicate a pair of bar supports, and 22A and 22B represent substantially C-shaped resilient supports supporting the bar supports 21A and 21B at or in the vicinity of their Bessel points to constitute a grid frame generally designated by 23. Reference numeral 24 identifies grid elements such as ribbonlike metal strips which are stretched between the pair of bar supports 21A and 21B at a predetermined tension distribution and pitch. These members are identical with those described in the foregoing examples.

In the present example, a damping rod formed of, for example, a metal wire is provided in contact with the grid elements 24.

For example, resilient pieces 26A and 26B are planted on the outside of the resilient supports 22A and 22B substantially at the center thereof, and the damping rod 25 is stretched between the resilient pieces 26A and 26B. In this case the damping rod 25 is stretched in a direction of the lines of the raster (in the electron beam-scanning direction) and it is preferred that the damping rod 25 be stretched obliquely in a range of 30° to 45° relative to the electron beam scanning direction.

With such an arrangement, the grid elements 24 are resiliently pressed by the damping rod 25, and hence are not likely to be caused to vibrate by mechanical shocks from the outside and electron beam bombardment. Even if vibration occurs, it is immediately suppressed by the damping rod 25, thus preventing a bad influence by the vibration of the grid elements. The provision of the damping rod 25 avoids not only the vibration of the grid elements but also irregularity in the spacing thereof which results from twisting of the grid elements. Namely, when the grid elements 24 are heated by collision of the electron beam therewith and are to be twisted due to thermal expansion, the damping rod 25 presses the grid elements 24 to prevent twisting of the grid elements to hold the space between adjacent grid elements as predetermined, ensuring that the electron beam impinges only on a predetermined phosphor strip. Further, the provision of the damping rod 25 is only to stretch it in contact with the surfaces of the grid elements and hence can be achieved with great ease. The damping rod 25 may be a mechanically strong metal wire of, for example, tungsten, stainless steel, inconel or the like. The use of such a mechanically strong wire avoids breakage of the damping rod or insufficient pressing of the grid elements as with conventional damping rods of glass fiber in grid structures for the Chromatron (Registered Trademark) type picture tubes.

The damping rod 25 formed of the above-mentioned metals or other ones is preferred in terms of mechanical strength and is free from secondary electron beam emission by the electron beam. It is preferred that the diameter of the damping rod 25 to 30 to 50 microns. With a diameter of, for example, 100 microns, the mechanical strength of the damping rod increases but the reproduced picture is adversely affected by the damping rod. With a diameter of less than 30 microns, the mechanical strength of the rod 25 decreases and its pressing effect of the grid elements becomes weak. With a smaller diameter damping rod, the bad influence on the reproduced picture is decreased correspondingly, but the influence of a damping rod 50 microns in diameter on the reproduced picture is hardly noticeable. According to our experiments, a tungsten wire of a diameter from 30 to 50 microns yields good results. In the foregoing example, the damping rod 25 is stretched between the two resilient pieces 26A and 26B but either or both of them may be dispensed with. The shape and position of the resilient pieces are not limited to those in the above example. For example, it is possible that resilient wires are stretched on the frame on both sides of the grid elements instead of the resilient pieces and the damping rod is stretched between the resilient wires. Further, the damping rod 25 may be attached to the grid elements 25.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

Electron beam scanning velocity modulation (svm) In beam scan velocity modulation (SVM) system for a television receiver,
in brief ,
a video signal is applied to a differentiator followed by a limiting differential amplifier. A driver amplifier coupled to the limiting amplifier drives an output stage that supplies current to an SVM coil. Certain video signals with large high frequency content may tend to produce excessive dissipation in the devices of the output stage. To prevent this, a current source for the differential amplifier is controlled by a voltage which is a measure of the average current through the output stage. The magnitude of the current source is varied to thereby vary the peak-to-peak signal output from the limiting amplifier to prevent overdissipation of the output devices. The presence of random noise in the video signal can produce unwanted SVM operation which can impair the viewed image. The unwanted noise component in the video signal can be reduced in amplitude by coring. The coring is unaffected by the variable limiting.

In a video signal reproducing apparatus having a cathode ray tube in which at least one electron beam is made to scan a screen in line-scanning and vertical directions while the intensity of the beam is modulated to establish the brightness of a video picture to be displayed on the screen, and in which bright picture portions are represented by respective high level portions of a video signal; a waveshaping circuit receives the video signal and acts thereon to provide a compensated video signal in which the width of each high level portion between the respective rising and falling edges is increased, the compensated video signal is employed to control the intensity of the electron beam, and the rising and falling edges of each high level portion of the compensated video signal are detected, as by a differentiating circuit or a delay line circuit, to provide respective output signals by which the scanning velocity of the beam in the line-scanning direction is modulated. The waveshaping circuit for providing the compensated video signal may be constituted by a delay line and an OR circuit having inputs to which the original video signal and the delayed video signal are applied, or by a differentiator receiving the original video signal and having its output applied to a polarity equalizer.

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What is claimed is: 1. A video signal reproducing apparatus comprising
a source of a video signal representing at least the brightness of a video picture and in which bright picture portions are represented by video signal portions of high level defined between respective rising and falling edges;
waveshaping means receiving said video signal from said source for providing a corresponding compensated video signal in which the width of each of said high level signal portions between said respective rising and falling edges is increased, said wave shaping means including delay means receiving said video signal from said source for providing a delayed video signal, and OR gate means having inputs receiving said video signal from said source and said delayed video signal, respectively, and an output at which said compensated video signal appears;
a cathode ray tube having a screen, an electron gun including beam producing means directing an electron beam generally along the axis of the tube toward said screen for impingement on the latter and being controlled in response to said compensated video signal from said waveshaping means so that the intensity of the beam is modulated in accordance with said compensated video signal, and deflection means for causing said beam to scan said screen in line-scanning and vertical directions, respectively;
detecting means also receiving said compensated video signal from said waveshaping means and detecting said rising and falling edges of the high level signal portions of said compensated video signal for providing output signals in correspondence to the detected rising and falling edges; and
beam velocity modulation means for modulating the scanning velocity of said electron beam in said line-scanning direction in accordance with said output signals from said detecting means.
2. A video signal reproducing apparatus according to claim 1; in which said OR gate means includes first and second transistors having respective collector-emitter paths connected in parallel between an operating voltage source and said output of the OR gate means, said first and second transistors further having respective base electrodes constituting said inputs receiving said video signal from said source thereof and said delayed video signal, respectively. 3. A video signal reproducing apparatus according to claim 1; in which said detecting means includes means differentiating said compensated video signal so as to provide said output signals in correspondence to said detected rising and falling edges. 4. A video signal reproducing apparatus comprising
a source of a video signal representing at least the brightness of a video picture and in which bright picture portions are represented by video signal portions of high level defined between respective rising and falling edges;
waveshaping means receiving said video signal from said source for providing a corresponding compensated video signal in which the width of each of said high level signal portions between said respective rising and falling edges is increased, said waveshaping means including differentiating means for differentiating the video signal from said source of the latter, polarity equalizing means acting on the differentiated signal from said differentiating means for providing a differentiated signal of one polarity, and adder means adding the video signal from said source thereof and said differentiated signal of one polarity to provide said compensated video signal;
a cathode ray tube having a screen, an electron gun including beam producing means directing an electron beam generally along the axis of the tube toward said screen for impingement on the latter and being controlled in response to said compensated video signal from said waveshaping means so that the intensity of the beam is modulated in accordance with said compensated video signal, and deflection means for causing said beam to scan said screen in line-scanning and vertical directions, respectively;
detecting means also receiving said compensated video signal from said waveshaping means and detecting said rising and falling edges of the high level signal portions of said compensated video signal for providing output signals in correspondence to the detected rising and falling edges; and
beam velocity modulation means for modulating the scanning velocity of said electron beam in said line-scanning direction in accordance with said output signals from said detecting means.
5. A video signal reproducing apparatus according to claim 4; in which said polarity equalizer includes a first diode connected in parallel with a series connection of an inventer and a second diode. 6. A video signal reproducing apparatus according to claim 4; in which said detecting means includes means differentiating said compensated video signal so as to provide said output signals in correspondence to said detected rising and falling edges. 7. A video signal reproducing apparatus comprising
a source of a video signal representing at least the brightness of a video picture and in which bright picture portions are represented by video signal portions of high level defined between respective rising and falling edges;
waveshaping means receiving said video signal from said source for providing a corresponding compensated video signal in which the width of each of said high level signal portions between said respective rising and falling edges is increased;
a cathode ray tube having a screen, an electron gun including beam producing means directing an electron beam generally along the axis of the tube toward said screen for impingement on the latter and being controlled in response to said compensated video signal from said waveshaping means so that the intensity of the beam is modulated in accordance with said compensated video signal, and deflection means for causing said beam to scan said screen in line-scanning and vertical directions, respectively;
detecting means also receiving said compensated video signal from said waveshaping means and detecting said rising and falling edges of the high level signal portions of said compensated video signal for providing output signals in correspondence to the detected rising and falling edges, said detecting means including means differentiating said compensated video signal so as to provide said output signals in correspondence to said detected rising and falling edges; and
beam velocity modulation means for modulating the scanning velocity of said electron beam in said line-scanning direction in accordance with said output signals from said detecting means.
8. A video signal reproducing apparatus comprising
a source of a video signal representing at least the brightness of a video picture and in which bright picture portions are represented by video signal portions of high level defined between respective rising and falling edges;
waveshaping means receiving said video signal from said source for providing a corresponding compensated video signal in which the width of each of said high level signal portions between said respective rising and falling edges is increased;
a cathode ray tube having a screen, an electron gun including beam producing means directing an electron beam generally along the axis of the tube toward said screen for impingement on the latter and being controlled in response to said compensated video signal from said waveshaping means so that the intensity of the beam is modulated in accordance with said compensated video signal, and deflection means for causing said beam to scan said screen in line-scanning and vertical directions, respectively;
detecting means also receiving said compensated video signal from said waveshaping means and detecting said rising and falling edges of high level signal portions of said compensated video signal for providing output signals in correspondence to the detected rising and falling edges; and
beam velocity modulation means for modulating the scanning velocity of said electron beam in said line-scanning direction in accordance with said output signals from said detecting means, said beam velocity modulation means including a tubular electrode on said axis of the tube for the passage of said electron beam axially through said tubular electrode between said beam producing means and said screen, said tubular electrode being in two parts which are axially separated along a vertical plane that is inclined relative to said axis of the tube, and means for applying said output signals from the detecting means across said two parts of the tubular electrode.
9. A video signal reproducing apparatus according to claim 8; in which said tubular electrode is included in electron lens means for focusing said beam at said screen, and said electron lens means further includes at least another tubular electrode arranged coaxially in respect to the first mentioned tubular electrode, with a relatively low potential being applied to said first tubular electrode and a relatively high potential being applied to said other electrode for producing an electrical field which effects said focusing of the beam.

Description:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to video signal reproducing apparatus, such as, television receivers, and more particularly is directed to providing such apparatus with improved arrangements for effecting electron beam scanning velocity modulation so as to significantly enhance the sharpness of the reproduced picture or image.
2. Description of the Prior Art
When the phosphor screen of a video signal reproducing apparatus, such as, the screen of the cathode ray tube in a television receiver, is scanned by an electron beam or beams so as to form a picture or image on the screen, the beam current varies with the luminance or brightness level of the input video signal. Therefore, each electron beam forms on the phosphor screen a beam spot whose size is larger at high brightness levels than at low brightness levels of the image so that sharpness of the reproduced picture is deteriorated, particularly at the demarcation between bright and dark portions on areas of the picture. Further, when a beam scanning the screen in the line-scanning direction moves across the demarcation or edge between dark and bright areas of the picture, for example, black and white areas, respectively, the frequency response of the receiver does not permit the beam intensity to change instantly from the low level characteristic of the black area to the high level characteristic of the white area. Therefore, the sharpness of the reproduced image is degraded at portions of the image where sudden changes in brightness occur in response to transient changes in the luminance or brightness of the video signal being reproduced. The increase in the beam current and in the beam spot size for bright portions of the reproduced picture or image and the inadequate frequency response of the television receiver to sudden changes in the brightness or luminance level of the incoming video signal are additive in respect to the degradation of the horizontal sharpness of the reproduced image or picture.
It has been proposed to compensate for the described degradation of the horizontal sharpness of the picture or image by employing the so-called "aperture correction or compensation technique," for example, as described in "Aperture Compensation for Television Camera," R. C. Dennison, RCA Review, 14,569 (1953). In accordance with such aperture correction or compensation technique, the intensity of the electron beam is first decreased and then increased at those portions of the picture image at which the brightness changes from a low level to a high level. Such modification or compensation of the electron beam intensity can be achieved by twice differentiating the original video signal so as to obtain a compensation signal which is added to the original video signal for obtaining a compensated video signal applied to the cathode of the cathode ray tube and having high level portions with relatively more steeply inclined rising and falling edges. However, with the foregoing aperture compensation technique, the peak luminance or brightness levels of the compensated video signal are increased and, as applied to the cathode of the cathode ray tube, result in beam currents that are increased relative to the maximum beam currents resulting from the original video signal so that the beam spot size is actually increased. By reason of the foregoing, the aperture compensation technique or method is insufficient for achieving really sharp definitions between light and dark areas of the reproduced picture or image, particularly in the case of relatively large screen areas, even though the described technique creates a visual edge effect which, to some extent, and particularly in the case of relatively small screens, registers psychologically as improved edge sharpness.
In order to avoid the above-described disadvantage of the aperture correction or compensation technique, it has been proposed to employ the so-called "beam velocity modulation method or technique" in which transient changes in the brightness level of the video signal are detected, and the scanning velocity of the electron beam in the line-scanning direction is modulated in accordance with the thus detected transient changes, for example, as described in detail in U.S. Pat. Nos. 2,227,630, 2,678,964, 3,752,916, 3,830,958 and 3,936,872, with the last two enumerated patents having a common assignee herewith.
More particularly, in the known beam velocity modulation technique or method, the original video signal representing brightness or luminance of a video picture and which incorporates "dullness" at abrupt changes in the luminance level due to the inadequate frequency response of the television receiver circuits to such abrupt changes in luminance level, is applied directly to the cathode or beam producing means of the cathode ray tube for modulating the intensity of the electron beam or beams, and such original video signal is also differentiated to obtain a modulation signal which is employed for effecting a supplemental horizontal deflection of the beam or beams in addition to the main or usual horizontal deflection thereof. The modulation or compensation signal may be supplied to the main deflection coil or yoke or to a supplemental deflection coil which is in addition to the main deflection coil with the result that the overall magnetic field acting on the beam or beams for effecting horizontal deflection thereof is modulated and corresponding modulation of the beam scanning velocity in the line-scanning direction is achieved. As is well known, the effect of the foregoing is to improve the sharpness of the image or picture in the horizontal direction. Since the original video signal is applied directly to the cathode or beam producing means of the cathode ray tube without increasing the level thereof at sharp changes in the brigheness level of the video signal, as in the aperture correction or compensation technique, the beam velocity modulation technique does not cause changes in the beam spot size so that sharpness of the image or picture in the horizontal direction is conspicuously improved.
However, it is a characteristic or inherent disadvantage of existing beam velocity modulation arrangements that the improved horizontal sharpness of the reproduced image or picture is achieved at the expense of a reduction in the width of the bright or white areas of the reproduced image or picture so that such bright or white areas are slimmer or more slender than would be the case if the depicted scene were accurately or precisely reproduced. OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a video signal reproducing apparatus with an improved arrangement for effecting beam scanning velocity modulation and thereby achieving enhanced sharpness of the reproduced image or picture, particularly at the demarcations between relatively dark and light picture areas, without reducing the widths of such light picture areas.
Another object is to provide an arrangement for effecting beam scanning velocity modulation, as aforesaid, which is relatively simple and is readily applicable to video signal reproducing apparatus, such as, television receivers.
In accordance with an aspect of this invention, in a video signal reproducing apparatus having a cathode ray tube in which at least one electron beam is made to scan a screen in line-scanning and vertical directions while the intensity of the beam is modulated to establish the brightness of a video picture to be displayed on the screen, and in which bright picture portions are represented by respective high level portions of an original video signal; a waveshaping circuit receives the original video signal and acts thereon to provide a compensated video signal in which the width of each high level portion between the respective rising and falling edges is increased, the compensated video signal is employed to control the intensity of the electron beam, and the rising and falling edges of each high level portion of the compensated video signal are detected to provide a respective output or modulation signal by which the scanning velocity of the beam in the line-scanning direction is modulated.
The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of illustrative embodiments thereof which is to be read in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B are diagrammatic views representing reproduced video pictures including bright and dark areas;
FIGS. 2A-2D are waveform or graphic views to which reference will be made in explaining the aperture correction or compensation technique of the prior art;
FIGS. 3A-3E are waveform or graphic views to which reference will be made in explaining the beam velocity modulation technique of the prior art and the disadvantage inherent therein;
FIG. 4 is a schematic view illustrating a circuit according to an embodiment of the present invention for effecting beam velocity modulation in a video signal reproducing apparatus;
FIG. 5 is an axial sectional view of an electron gun in a cathode ray tube which is particularly suited for use with a beam velocity modulation arrangement according to this invention;
FIGS. 6A-6F are waveforms or graphic views to which reference will be made in explaining the operation of the circuit according to this invention as shown on FIG. 4;
FIG. 7 is a schematic view illustrating another embodiment of a portion of the circuit shown on FIG. 4 for effecting beam velocity modulation according to this invention;
FIGS. 8A-8D are waveforms or graphic views to which reference will be made in explaining the operation of the embodiment of this invention illustrated by FIG. 7;
FIG. 9 is a diagrammatic view illustrating a circuit that may be used for one of the components shown on FIG. 7; and
FIG. 10 is a wiring diagram illustrating another embodiment of a portion of the circuit shown on FIG. 4 for effecting beam velocity modulation in accordance with this invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in detail, and initially to FIG. 4 thereof, it will be seen that the present invention is related to a television receiver or other video signal reproducing apparatus 10 having a cathode ray tube 11 in which a beam producing means including a cathode 12 directs an electron beam B generally along the axis of the tube envelope toward a phosphor screen S on the faceplate of the tube. In the apparatus 10, the intensity of electron beam B, and hence the brightness of the beam spot produced at the location where the beam B impinges on screen S, is modulated in accordance with a video signal applied to cathode 12 and representing at least the brightness of a video picture to be reproduced on screen S. The cathode ray tube 11 is further shown to include the conventional deflection means or yoke 13 by which beam B is made to scan screen S in the line-scanning or horizontal and vertical directions, respectively. The simultaneous modulation of the beam intensity by the video signal applied to cathode 12 and the scanning of screen S by beam B in response to sweep signals applied to yoke 13 will result in the reproduction of an image or picture on screen S. The image or picture reproduced on screen S may be constituted by at least one white or bright picture portion, for example, in the form of a rectangle as shown at 14a on FIG. 1A, or in the form of a vertical line as indicated at 14b on FIG. 1B, and relatively darker picture portions. In any case, it will be understood that, in each line or horizontal interval of a video signal received by a television receiver and utilized in the cathode ray tube of the latter for reproducing a horizontal increment of an image or picture at a vertical position in the latter which is included in the bright or white area 14a or line 14b, the respective bright picture portion is represented by a corresponding high level video signal portion defined between rising and falling edges 15r and 15f, respectively (FIG. 2A). If the transmitted video signal S T is to represent a white or bright shape or area surrounded by a black or very dark background with a sharp demarcation therebetween, the rising and falling edges 15r and 15f of the high level signal portion will be precipitous, that is, substantially vertical, as shown, so as to represent the desired high frequency change in luminance level. However, the usual television receiver circuit, for example, comprised of RF and IF amplifiers and a video detector, and by which the video signal to be used in the cathode ray tube is derived from the received television signal, has a frequency response that is inadequate to accommodate the mentioned high frequency components of the transmitted video signal S T . Thus, the video signal S O (FIG. 2B) which is available in the television receiver for controlling the intensity of the electron beam or beams in the cathode ray tube is relatively "dull" that is, it has decreased high frequency components, as represented by the illustrated sloping, rising and falling edges 16r and 16f of the high level signal portion. Such relatively dull video signal S O is hereinafter referred to as the "original video signal," and such terminology is reasonable when considered from the point of view of the input side of the cathode ray tube. Further, the term "original video signal" has often been used in the prior art in the same sense that it is used herein.
The decrease in the high frequency components of the original video signal S o as compared with the transmitted video signal S T causes a decrease in the horizontal sharpness of the reproduced image or picture, that is, the sloping, rising and falling edges 16r and 16f (FIG. 2B) result in a gradual change from dark to bright and from bright to dark, respectively, rather than in the sudden changes in brightness represented by the transmitted signal S T (FIG. 2A). Horizontal sharpness of the reproduced image or picture is furthermore decreased by the fact that, in the cathode ray tube, the electron beam current varies with the luminance or brightness level of the video signal applied to the cathode ray tube and, when the luminance level is high, for example, to represent a bright or white area of the picture, the beam spot size caused by impingement of the electron beam on the phosphor screen is enlarged to further decrease or deteriorate the sharpness of the reproduced picture.
In seeking to compensate for the above-described lack of sharpness of the reproduced picture by the known aperture correction or compensation technique, the original video signal S O (FIG. 2B) is differentiated twice so as to obtain a compensation signal S B (FIG. 2C) which is added to the original video signal S O for providing a compensated video signal S C (FIG. 2D). As shown, the compensated video signal S C has rising and falling edges 17r and 17f which are more steeply inclined than the corresponding rising and falling edges 16r and 16f of the original video signal S O . However, when the compensated video signal S C is applied to the cathode of a cathode ray tube for controlling the intensity or beam current of the electron beam or beams therein, the sharpness of the reproduced picture is not conspicuously improved. The foregoing results from the fact that, by adding the compensation signal S B to the original video signal S O for obtaining the compensated video signal S C applied to the cathode of the cathode ray tube, the maximum beam current corresponding to the peak luminance level of signal S C is increased, as compared with the maximum beam current corresponding to the peak luminance level of original video signal S O , with the result that the beam spot size resulting from compensated video signal S C is enlarged. Such enlargement of the beam spot size causes a decrease in sharpness of the reproduced picture, as previously noted, and thus substantially defeats any increase in sharpness that might result from the relatively more steeply inclined rising and falling edges 17r and 17f of the compensated video signal S C .
In the known beam velocity modulation technique for improving horizontal sharpness of the reproduced image or picture, the dull original video signal S O (FIG. 3A) is applied, without alteration, to the cathode or beam producing means of the cathode ray tube for determining the intensity or beam current of the electron beam or beams in the cathode ray tube. The original video signal S O is also subjected to differentiation to obtain a compensation signal S A (FIG. 3B). The compensation signal S A is applied to a supplemental deflection means which is in addition to the main deflection coils or yoke so that the horizontal deflection field for effecting scanning movement of each beam in the line-scanning direction is modified or compensated, as shown on FIG. 3C. As a result of such modified or compensated horizontal deflection field, the beam scanning velocity in the line-scanning direction, is modulated as shown on FIG. 3D. It will be appreciated that, during each period T a on FIG. 3D, the beam scanning velocity is increased so that a decreased amount of light is emitted from the phosphor dots or areas on the screen that are impinged upon during each period T a . On the other hand, during each period T b , the beam velocity is decreased so that an increased amount of light is emitted from the phosphor dots or areas impinged upon by the electron beam during each period T b . Therefore, the variation, in the horizontal direction across the screen, in the amount of emitted light, is substantially as indicated on FIG. 3E, from which it will be apparent that the sharpness of the reproduced image or picture in the horizontal direction is improved. Since the original video signal S O is still applied to the cathode of the cathode ray tube for controlling the beam intensity, the beam spot size is not changed or increased by reason of the beam velocity modulation and, therefore, the improvement in sharpness in the horizontal direction is not adversely affected by increasing beam spot size, as in the aperture correction or compensation technique. However, the conventional beam velocity modulation technique still has the disadvantage that the width of each white or bright portion of the picture or image reproduced on the screen is less than that which would result from the original video signal S o in the absence of the beam velocity modulation, as is apparent from the comparison of FIG. 3E with FIG. 3A.
Generally, in order to avoid the foregoing disadvantage of the previously known beam velocity modulation technique, the present invention employs a waveshaping circuit receiving the original video signal and providing a corresponding compensated video signal in which the width of each high level signal portion is increased relative to the corresponding width of the original video signal. The compensated video signal from the mentioned waveshaping circuit is applied to the cathode or beam producing means of the cathode ray tube for modulating the intensity of the electron beam or beams therein in accordance with the compensated video signal, while the rising and falling edges of the high level signal portions of the compensated video signal are detected to provide a corresponding output or modulating signal applied to the beam velocity modulation means for modulating the scanning velocity of the electron beam or beams in accordance with such output signal. Referring in detail to FIG. 4, it will be seen that, in the video signal reproducing apparatus 10 according to this invention, as there shown, an antenna 18 receives a television signal which includes the transmitted video signal S T (FIG. 2A) and applies the same to conventional video circuits indicated schematically at 19 and which include the usual RF and IF amplifiers and video detector for deriving the original video signal S O (FIG. 6A) from the received television signal. As noted, the video circuits 19 of television receiver 10 are conventional so that no detailed explanation thereof will be included herein. The video signal from circuit 19 is supplied through a video amplifier 20 to a waveshaping circuit 21 which, in accordance with this invention, is operative to increase the width of each high level portion of the original video signal S O from video amplifier 20.

The waveshaping circuit 21 is shown to include a pair of transistors 22 and 23 having their collectors connected together to an operating voltage source +V cc , while the emitters of transistors 22 and 23 are connected together to one end of a resistor 24 having its other end connected to ground. The original video signal S O (FIG. 6A) is applied to the base of transistor 22 from video amplifier 20 through a resistor 25, and the base of transistor 22 is further connected to ground through a resistor 26. The original video signal S O from video amplifier 20 is further applied through a resistor 27 and a delay line 28 to the base of transistor 23 which is further connected to ground through a resistor 29. The resistors 27 and 29 provide impedance matching for the delay line 28, while the resistors 25 and 26 are provided for level adjusting purposes, that is, to ensure that the level of the original video signal S O applied to the base of transistor 22 from video amplifier 20 will be equal to the level of the delayed video signal S D (FIG. 6B) applied to the base of transistor 23 and which is delayed by the time τ in respect to the original video signal. Finally, the output of waveshaping circuit 21 is derived from a connection point between the emitters of transistors 22 and 23 and resistor 24.
It will be apparent that, during the period T A (FIG. 6C), the level of original video signal S O applied to the base of transistor 22 is higher than the level of the delayed video signal S D applied to the base of transistor 23, so that transistor 22 is turned ON and transistor 23 is turned OFF. During the next period T B , at which time both original video signal S O and delayed video signal S D are at the same level, transistors 22 and 23 are both turned ON. Finally, during the concluding period T C , the level of delayed video signal S D is higher than the level of original video signal S O , so that transistor 22 is turned OFF and transistor 23 is turned ON. Thus, as is apparent on FIG. 6C, the level of the compensated video signal S K obtained across resistor 24, that is, at the output of waveshaping circuit 21, is equal to the level of the input video signal S O during the period T A , is equal to the level of either the original video signal S O or the delayed video signal S D during the period T B , and is equal to the level of the delayed video signal S D during the period T C . In other words, transistors 22 and 23 of waveshaping circuit 21 operate as an OR gate circuit in respect to the original video signal S O and the delayed video signal S D applied to the two inputs of such OR circuit defined by the base electrodes of the two transistors. Further, by comparing the compensated video signal S K (FIG. 6C) with the original video signal S O (FIG. 6A), it will be appreciated that the effect of waveshaping circuit 21 is to increase the width of each high level portion of the original or incomming video signal.
Referring again to FIG. 4, it will be seen that the compensated video signal S K is applied through a video amplifier 30 to the cathode electrode 12 of cathode ray tube 11 for modulating the intensity of electron beam B therein. Simultaneously, the rising and falling edges of the high level signal portions of compensated video signal S K are detected to provide a corresponding output or modulating signal by which the scanning velocity of the electron beam B in the line-scanning direction is modulated. More particularly, in the television receiver 10 of FIG. 4, the compensated video signal S K from waveshaping circuit 21 is applied to a differentiation circuit 31 which acts as a detector for detecting the rising and falling edges of the compensated video signal and which provides a corresponding output signal in the form of a differentiated signal S V (FIG. 6D). Such differentiated signal S V is applied to a beam velocity modulation means, for example, in the form of the supplemental deflection device 32 of FIG. 4, for modulating the scanning velocity of the electron beam B in the line-scanning direction in accordance with the differentiated signal S V from differentiator 31. The supplemental deflection device 32 may be constituted, as shown, by two spaced apart plate-like electrodes 32a and 32b directed vertically in cathode ray tube 11 and arranged for the passage of electron beam B therebetween, with the differentiated signal S V being applied across the plate-like electrodes 32a and 32b so as to produce a corresponding electrical field by which the scanning velocity of the beam, in the line-scanning direction, is modulated, for example, as shown on FIG. 6E.
Although the beam velocity modulation means is, in the embodiment of FIG. 4, constituted by a supplemental deflection device 32 in the form of a pair of plate-like electrodes 32a, 32b across which the output of differentiation circuit 31 is applied, the present invention is preferably employed in connection with a cathode ray tube of the type disclosed in detail by U.S. Pat. No. 3,936,872, and having an electron gun provided with a special focusing electrode to also function as the beam velocity modulating means, as shown on FIG. 5. More particularly, in the cathode ray tube 11A of FIG. 5, the neck portion 33 of the tube envelope is shown to contain an electron gun structure including a cathode 12a, a control electrode or grid 35, an acceleration electrode or grid 36, a first anode electrode 37, a focusing electrode 38 and a second electrode 39 all arranged successively in axial alignment along the central axis 40 of the cathode ray tube. The focusing electrode 38 is shown to be tubular and to be formed in two parts 38a and 38b which are axially separated along a vertical plane that is inclined relative to the axis 40 of the tube. For the operation of electron gun 34, appropriate static or bias voltages are applied to grids 35 and 36 and to electrodes 37, 38 and 39. Thus, for example, a voltage of zero to -400 V. may be applied to grid 35, a voltage of zero to 500 V may be applied to grid 36, a relatively high voltage or potential, for example, an anode voltage of 13 to 20 KV. may be applied to electrodes 37 and 39, and a relatively low voltage or potential of zero to only several KV. may be applied to parts 38a and 38b of electrode 38, with all of the foregoing voltages being upon the bias voltage applied to cathode 12a as a reference. With the foregoing voltage distribution, an electron lens field is established around the axis of electrode 38 by the electrodes 37, 38 and 39 to form a main focusing lens by which the electron beam is focused at the screen of the cathode ray tube. Furthermore, the differentiated or modulation signal S V from differentiation circuit 31 of FIG. 4 is applied between parts 38a and 38b of electrode 38 in superposed relation to the static or bias voltage applied to electrode 38 for forming the focusing lens. It will be apparent that, by reason of the described diagonal separation between parts 38a and 38b of focusing lens electrode 38, the application of the differentiated signal or modulation signal S V across electrode parts 38a and 38b results in a respective electric field which is operative to deflect the electron beam or beams in the horizontal or line-scanning direction. Thus, the beam velocity in the line-scanning direction is modulated accordingly.
Whether the velocity modulation signal S V is applied to the plates 32a and 32b of supplemental deflection device 32, or across the parts 38a and 38b of focusing electrode 38, it will be seen that, in accordance with this invention, such velocity modulation signal S V (FIG. 6D) for effecting beam velocity modulation in the line-scanning direction is derived from the compensated video signal S K (FIG. 6C) in which the width of each bright or white signal portion is enlarged as compared with the width thereof in the original video signal S O (FIG. 6A). Therefore, the intensity of light emission is changed or varied in the horizontal direction across the screen in the manner represented by FIG. 6F, from which it is apparent that the sharpness of the reproduced image or picture in the horizontal direction is substantially improved. Furthermore, from a comparison of FIG. 6F with FIG. 6A, it will be apparent that, by a proper selection of the delay time τ of delay line 28, the width of the white or bright portion of the reproduced image or picture is not substantially decreased and may be made to accurately correspond to the width of corresponding high level portion of the original video signal. Therefore, the previously described disadvantage of the known technique for effecting beam velocity modulation has been avoided by the present invention.
Referring now to FIG. 7, it will be seen that, in accordance with another embodiment of this invention, a waveshaping circuit 21' which can be substituted for the waveshaping circuit 21 in the apparatus 10 of FIG. 4, includes a differentiation circuit 41, a polarity equalizer 42 and an adding circuit 43. The original video signal S O (FIG. 8A) from video amplifier 20 on FIG. 4 is applied directly to one input of adding circuit 43 and also to differentiation circuit 41 which provides a corresponding differentiated signal S A (FIG. 8B). The differentiated signal S A from circuit 41 is applied to polarity equalizer 42 in which the negative polarity portion of the differentiated signal S A , which corresponds to the falling edge of the original video signal S O , is inverted so as to have a positive polarity. The resulting polarity equalized signal S E (FIG. 8C) is applied to another input of adder circuit 43 so as to be added in the latter to the original video signal S O and thereby obtain the compensated video signal S K (FIG. 8D). Such compensated video signal S K shown on FIG. 8D corresponds generally to the compensated video signal S K previously described with reference to FIG. 6C, and is similarly applicable to amplifier 30 and differentiation circuit 31 of FIG. 4. It will be apparent that the compensated video signal S K (FIG. 8D) obtained from waveshaping circuit 21' also has the width of its high level signal portions enlarged relative to the widths of such signal portions in the original video signal S O . Therefore, when the compensated video signal S K from waveshaping circuit 21' is applied through amplifier 30 to cathode 12 of cathode ray tube 11 and also to differentiation circuit 31 to form therefrom the beam velocity modulation signal S V applied to the supplemental deflection device 32, the resulting beam velocity modulation is performed in the same manner as described above with reference to FIG. 4 so as to obtain improved horizontal sharpness of the resulting reproduced picture or image without narrowing of the bright or white areas of such image or picture. As shown on FIG. 9, the polarity equalizer 42 employed in the waveshaping circuit 21' of FIG. 7 may simply consist of a first diode 44 connected in parallel with a series connection of an inverter 45 and a second diode 46. The diodes 44 and 46 both have the same polarity so that the positive polarity portion of the differentiated signal S A passes through diode 44, while the negative polarity portion of signal S A , after being inverted by inverter 45, passes through diode 46.
In the embodiment of the invention described above with reference to FIG. 4, the differentiation circuit 31 is employed for detecting the rising and falling edges of the high level signal portions of the compensated video signal S K and for providing output signals or beam velocity modulation signals in correspondence to the detected rising and falling edges. However, reference to FIG. 10 will show that a circuit 31' of a type disclosed in detail in U.S. Pat. No. 3,936,872, may be employed in place of differentiation circuit 31 for providing the desired beam velocity modulating signal. More particularly, circuit 31' is known to contain a single delay line 47 having input and output ends 47a and 47b, with the compensated video signal S K being applied to input end 47a by way of a transistor 48 of collector-common configuration which acts to amplify the signal without altering the phase thereof. More specifically, as shown, the compensated video signal S K is applied to the base electrode of transistor 48 which has its collector connected to ground, while the emitter of transistor 48 is connected through a resistor 49 to an operating voltage source +V cc , and through a resistor 50 to the input end 47a of delay line 47. Further, as shown, the output end 47b of delay line 47 is connected through a bleeder resistor 51 to ground, and is also connected to a transistor 52 of base-common configuration which acts as an impedance converter. More specifically, transistor 52 is shown to have its emitter connected to the output end 47b of delay line 47 while its base electrode is connected to ground through a capacitor 53 and also connected between biasing resistors 54 and 55 which are connected in series between operating voltage source +V cc and ground. Finally, a resistor 56 is connected between the operating voltage source and the collector of transistor 52, and output terminals 57 and 58 are respectively connected to the input end 47a of delay line 47 and to the collector of transistor 52.
In circuit 31', bleeder resistor 51 is dimensioned to provide a relatively small current flow therethrough, while the input impedance, that is, the base-emitter impedance of transistor 52 is very small in respect to the impedance of resistor 51. Therefore, in response to a transient or sharp change in the compensated video signal transmitted along delay line 47, the output end 47b of the latter is shorted to ground so as to cause a negative reflected wave to travel back along delay line 47 to its input end 47a. As a result of the foregoing, the resistor 56 detects the short circuit current at the output end of delay line 47, and more precisely at the collector of transistor 52, so as to provide a corresponding voltage or signal S K1 at output terminal 58 which corresponds to the compensated video signal S K once delayed by the delay line 47. Further, the reflected wave returning to the input end of delay line 47 in response to a transient change in the compensated video signal S K results in a signal S K2 that corresponds to the signal S K twice delayed by the delay line 47. Therefore, in response to a transient change in the signal S K , there is obtained at output terminal 57 a signal S V1 equal to the difference between compensated video signal S K and the twice delayed signal S K2 . When using the circuit 31 of FIG. 10 in place of the differentiation circuit 31 in the apparatus of FIG. 4, the output signal S K1 is applied to the cathode 12 of the cathode ray tube 11 for controlling the intensity of the electron beam, while the output signal S V1 is applied from circuit 31' to supplemental deflecting device 32 for effecting the beam scanning velocity modulation.
In the above described embodiments of the invention, the signal S V or S V1 for controlling the beam scanning velocity modulation has been applied across the plates 32a and 32b of the supplemental deflection device 32 or across the parts 38a and 38b of the focusing lens electrode 38. However, it will be understood that, in all of the described embodiments of the invention, the signal S V or S V1 from circuits 31 or 31', respectively, can be superimposed on the horizontal sweep or deflection signal and applied with the latter to the horizontal deflection coil of the main deflection yoke 13 so as to again modulate the beam scanning velocity in the line scanning direction.
Further, in FIGS. 4 and 5 of the drawings, the invention has been illustrated as applied to a monochrome television receiver for modulating the beam scanning velocity of a single electron beam in the cathode ray tube 11 or 11A. However, it will be understood that the invention is similarly applicable to a color television receiver in which the luminance component of the color television signal is the video signal that is compensated in circuit 21 or 21' and then detected in circuit 31 or 31'.
In any event, it will be apparent that, in a television receiver or other video signal reproducing apparatus according to this invention, the sharpness of the reproduced image or picture is improved without a decrease in the width of the relatively bright or white areas of the reproduced picture.
Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope of the invention, as defined inthe appended claims.

In a single-gun, plural-beam color picture tube in which two beams emerge from a focusing lens along paths that diverge from a central beam emerging along the optical axis of the lens by which all of the beams are focused on the color screen, and the divergent beams are deflected to converge with the central beam by passage through respective electrical fields established between first spaced plates, at opposite sides of the central beam path, and second plates spaced outwardly from the first plates; such plates are disposed closely adjacent to the main deflection yoke by which the beams are made to scan the screen so that the length of the tube can be minimized, and the misconvergence of the beams that may result from the magnetic field produced between the first plates by reason of a current flow induced in the first plates by flux change of the magnetic field of the main deflection yoke is corrected by providing the second plates with different dimensional relationships to the first plates, for example, different distances from the first plates or different distances along the first plates, so that the deflecting effects of the electrical fields are correspondingly different.

1. A plural beam color picture tube comprising a color screen having arrays of color phosphors and beam selecting means with apertures corresponding to said arrays, beam-generating means for directing a plurality of electron beams toward said color screen for impingement on respective phosphors of each array through the corresponding aperture, lens means for focusing said electron beams on said color screen and having an optical center through which all of said beams are passed with one of said beams passing through said lens means along the optical axis of the latter and two of said beams being angled with respect to said optical axis to emerge from said lens means along paths divergent to said axis, electron beam convergence deflecting means interposed between said lens means and said beam selecting means for deflecting said two beams emerging along said divergent paths so as to achieve convergence of all of said beams at an aperture of said beam-selecting means, and magnetic yoke means also interposed between said lens means and said beam-selecting means to produce a magnetic field by which said beams are simultaneously deflected to scan said screen; said convergence deflecting means including first interconnected plates which are spaced apart for the passage of said one beam therebetween, second plates spaced outwardly from said first plates so that each of said two beams passes between a first plate and a second plate and means to apply one voltage to said first plates and a different voltage to said second plates so that the voltage difference between said first plates and said second plates produces electrical fields therebetween for effecting said convergence, said convergence deflecting means being disposed closely adjacent to said magnetic yoke means so as to reduce the necessary length of the tube and as a result of which said magnetic field of the yoke means induces a current flow through said interconnected first plates producing a magnetic field between said first plates which acts on said one beam to cause misconvergence of the beams, and said misconvergence being corrected by providing one of said second plates with different dimensional relationships to its corresponding first plate than the other of said second plates has to its corresponding first plate so that said electrical fields exert unequal deflecting effects on said two beams in coaction with the field of said magnetic yoke means for restoring the convergence thereof with said one beam.

2. A plural-beam color picture tube according to claim 1, in which said second plates are spaced from the respective first plates by different distances so that the flux densities of said electrical fields are different.

3. A plural-beam color picture tube according to claim 1, in which said second plates extend for different distances along the respective first plates in the direction of said beams therebetween so that said two beams pass for different distances through the respective electrical fields.

4. A plural-beam color picture tube according to claim 1, in which said convergence deflecting means and said magnetic yoke means overlap in the direction of the axis of the tube.

Description:

This invention relates generally to plural-beam color picture tubes, and particularly to tubes of that type in which the plural beams are passed through the optical center of a common electron lens by which the beams are focused on the color phosphor screen so as to eliminate coma and spherical aberration by reason of the lens.

In plural-beam color picture tubes of the described type, for example, in the single-gun tube as specifically disclosed in the copending U.S. application Ser. No. 697,414, filed Jan. 12, 1968 now U.S. Pat. No. 3,448,316 and having a common assignee herewith, three laterally spaced electron beams are emitted or originated by a beam generating or cathode assembly and directed in a common substantially horizontal or vertical plane with the central beam coinciding with the optical axis of the single electron focusing lens and the two outer beams being converged to cross the central beam at the optical center of the lens and thus emerge from the latter along paths that are divergent from the optical axis. Arranged between the focusing lens and the color screen is an electrostatic convergence deflecting means by which the beams divergent from the optical axis are deflected substantially in the plane of origination thereof for causing all of the beams to converge at a common location on a beam-selecting means, such as an aperture grill, and to pass therethrough for impingement on respective color phosphors of a color screen. Further, between the focusing lens and the beam-selecting means, the beams are acted upon by the magnetic fields resulting from the application of horizontal and vertical sweep signals to a main deflection yoke, whereby the beams are made to scan the screen in the desired raster. The convergence deflecting means of the foregoing color picture tube conveniently comprises a first pair of interconnected, spaced plates between which the central beam is passed, and a second pair of plates spaced outwardly from the first plates so that the divergent beams are passed between the first and second plates to be deflected for convergence by electrical fields provided therebetween when one voltage is applied to both first plates and a different voltage is applied to both second plates.

If the above convergence deflecting plates are to be remote from the magnetic fields of the main deflection yoke, the length of the neck of the tube envelope is undesirably increased and requires a corresponding increase in the depth of the television receiver cabinet to accommodate the tube. On the other hand, if the neck portion of the tube is shortened, which requires that the convergence deflection plates extend closely adjacent to the main deflection yoke, a magnetic field of the latter induces a current flow in the closed path constituted by the interconnected first plates between which the central beam is passed, and such current flow produces a magnetic field that deflects the central beam away from accurate convergence with the other two beams.

Accordingly, it is an object of this invention to provide a plural-beam color picture tube of the described type in which the convergence deflection plates are closely adjacent to, or even axially overlapped with respect to the main deflection yoke so as to minimize the necessary length of the neck portion of the tube envelope, and further in which any misconvergence that would result from the proximity of the convergence deflection plates to the main deflection yoke is avoided.

In accordance with an aspect of this invention, the misconvergence that would result from the proximity of the convergence deflection plates to the main deflection yoke is compensated for by providing the second or outer convergence deflection plates with different dimensional relationships to the respective first convergence deflection plates so that the electrical fields established between the first and second plates exert unequal deflecting effects on the beams passing therethrough. The different dimensional relationships mentioned above may involve different spacings between the first and second plates for deflecting one of the divergent beams and between the first and second plates for deflecting the other divergent beam, so that the flux densities are different in the electric fields traversed by the two divergent beams. Alternatively, or in combination with the foregoing, the different dimensional relationship may be provided by giving the second plates different dimensions in the direction along the respective first plates so that the two divergent beams pass for different distances through the respective electric fields.

The above, and other objects, features and advantages of this invention, will be apparent in the following detailed description of illustrative embodiments thereof which is to be read in connection with the accompanying drawing, in which:

FIG. 1 is a schematic sectional view in a horizontal plane passing through the axis of a single-gun, plural-beam color picture tube of the type to which this invention is preferably applied;

FIG. 2 is a fragmentary sectional view taken in the same plane as FIG. 1, and which shows the structural arrangement of a portion of such tube in order to reduce the length of the neck portion of the tube envelope;

FIG. 3 is a transverse sectional view taken along the line 3-3 on FIG. 2; and

FIGS. 4 and 5 are fragmentary sectional views showing the arrangements of the convergence deflection plates in a tube as shown on FIGS. 2 and 3 in order to avoid misconvergence in accordance with two respective embodiments of this invention.

Referring to the drawings in detail, and initially to FIG. 1 thereof, it will be seen that a single-gun, plural-beam color picture tube 10 of the type to which this invention may be applied comprises a glass envelope (not shown) having a neck and a cone extending from the neck to a color screen S provided with the usual arrays of color phosphors S R , S G and S B and with an apertured beam-selecting grill or shadow mask G P . Disposed within the neck is a single electron gun A having cathodes K R , K G and K B , each of which is constituted by a beam-generating source with the respective beam-generating surfaces thereof disposed as shown in a plane which is substantially perpendicular to the axis of the electron gun. The beam-generating surfaces are arranged in a straight line so that the respective beams B R , B G and B B emitted therefrom are directed in a substantially horizontal or other common plane containing the axis of the gun, with the central beam B G being coincident with such axis. A first grid G 1 is spaced from the beam-generating surfaces of cathodes K R , K G and K B and has apertures g 1R , g 1G , and g 1B formed therein in alignment with the respective cathode beam-generating surfaces. A common grid G 2 is spaced from the first grid G 1 and has apertures g 2R , g 2G and g 2B formed therein in alignment with the respective apertures of the first grid G 1 . Successively arranged in the axial direction away from the common grid G 2 are open-ended, tubular grids or electrodes G 3 , G 4 and G 5 , respectively, with cathodes K R , K G and K B , grids G 1 and G 2 , and electrodes G 3 , G 4 and G 5 being maintained in the depicted, assembled positions thereof, by suitable, nonillustrated support means of an insulating material.

For operation of the electron gun of FIG. 1, appropriate voltages are applied to the grids G 1 and G 2 and to the electrodes G 3 , G 4 and G 5 . Thus, for example, a voltage of 0 to minus 400 v. is applied to the grid G 1 , a voltage of 0 to 500 v. is applied to the grid G 2 , a voltage of 13 to 20 kv. is applied to the electrodes G 3 and G 5 , and a voltage of 0 to 400 v. is applied to the electrode G 4 , with all of these voltages being based upon the cathode voltage as a reference. As a result, the voltage distributions between the respective electrodes and cathodes, and the respective lengths and diameters thereof, may be substantially identical with those of a unipotential-single beam-type electron gun which is constituted by a single cathode and first and second, single-apertured grids.

With the applied voltage distribution as described hereinabove, an electron lens field will be established between grid G 2 and the electrode G 3 to form an auxiliary lens L' as indicated in dashed lines, and an electron lens field will be established around the axis of electrode G 4 , by the electrodes G 3 , G 4 and G 5 , to form a main focusing lens L, again as indicated in dashed lines. In a typical use of electron gun A, bias voltages of 100 v., 0 v., 300 v., 20 kv., 200 v. and 20 v. may be applied respectively to the cathodes K R , K G and K B , the first and second grids G 1 and G 2 and the electrodes G 3 , G 4 and G 5 .

Further included in the electron gun of FIG. 1 are electron beam convergence deflecting means F which comprise a first pair of shielding plates P and P' disposed in the depicted spaced, relationship at opposite sides of the gun axis, and a second pair of axially extending, deflector plates Q and Q' which are disposed, as shown, in outwardly spaced, opposed relationship to shielding plates P and P', respectively. Although depicted as substantially straight, it is to be understood that the deflector plates Q and Q' may, alternatively, be somewhat curved or outwardly bowed, as is well known in the art.

The shielding plates P and P' are equally charged and disposed so that the central electron beam B G will pass substantially undeflected between the shielding plates P and P', while the deflector plates Q and Q' have negative charges with respect to the plates P and P' so that respective electron beams B B and B R will be convergently deflected as shown by the respective passages thereof between the plates P and Q and the plates P' and Q'. More specifically, a voltage V P which is equal to the voltage applied to the electrode G 5 , may be applied to both shielding plates P and P', and a voltage V Q , which is some 200 to 300 v. lower than the voltage V P , may be applied to the respective deflector plates Q and Q' to result in the respective shielding plates P and P' being at the same potential, and to result in the application of a deflecting voltage difference or convergence deflecting voltages between plates P' and Q' and plates P and Q and it is, of course, this convergence deflecting voltage V C which will produce electric fields to impart the requisite convergent deflection to electron beams B B and B R .

In operation, the electron beams B R , B G and B B which emanate from the beam-generating surfaces of the cathodes K R , K G and K B will pass through the respective grid apertures g 1R , g 1G and g 1B , to be intensity modulated with what may be termed the "red," "green" and "blue" intensity modulation signals applied between the said cathodes and the first grid G 1 . The respective electron beams will then pass through the common auxiliary lens L' to cross each other at the center of the main lens L and to emerge from the latter with beams B R and B B diverging from beam B G . Thereafter, the central electron beam B G will pass substantially undeflected between shielding plates P and P' since the latter are at the same potential. Passage of the electron beam B B between the plates P' and Q' and of the electron beam B R between the plates P and Q will, however, result in the convergent deflections thereof as a result of the convergence deflecting voltage applied therebetween, and the system of FIG. 1 is intended to be so arranged that electron beams B B , B G and B R will desirably converge or cross each other at a common spot centered in an aperture of the beam-selecting grill G P and then diverge therefrom to strike the respective color phosphors of a corresponding array thereof on screen S. More specifically, it may be noted that the color phosphor screen S is composed of a large plurality of sets or arrays of vertically extending "red," "green" and "blue" phosphor stripes or dots S R , S G and S B with each of the arrays or sets of color phosphors forming a color picture element. It will be understood that the common spot of beam convergence corresponds to one of the thusly formed color picture elements.

Electron beam scanning of the face of the color phosphor screen is effected by horizontal and vertical deflection yoke means indicated in broken lines at D and which receives horizontal and vertical sweep signals whereby a color picture will be provided on the color screen. Since, with this arrangement, the electron beams are each passed, for focusing, through the center of the main lens L of electron gun A, the beam spots formed by impingement of the beams on the color phosphor screen S will be substantially free from the effects of coma and/or astigmatism of the main lens, whereby improved color picture resolution will be provided.

As shown on FIGS. 2 and 3, the plates P and P', in a structural embodiment of the tube schematically illustrated on FIG. 1, may be supported, at the sides of their ends closest to electrode G 5 , by angle members 12 and 13 secured to a flange 11 at the adjacent end of a tubular extension of electrode G 5 which is, in turn, supported within tube neck N by insulating discs 24 and 25 having getter rings 22 and 23 suitably mounted therebetween. The forward ends of plates P and P' are joined, at the sides of the latter, by bracing members 21 extending therebetween. The voltage V P is applied to plates P and P' through a contact spring 18 extending from one of the bracing members 21 into engagement with a conductive coating 17 which is applied to the inner surface of the cone portion C of the tube envelope and extends into the adjacent neck portion thereof. The voltage V P is applied to coating 17 by way of an anode button (not shown) provided in cone portion C, and is applied to electrode G 5 from plates P and P' by way of angle members 12 and 13. From electrode G 5 , the voltage V P may be applied to electrode G 3 by way of a suitable conductor (not shown). The voltage V P may also be applied to aperture grill G P , as an anode voltage, by way of coating 17.

Posts or pins 14 extend outwardly from plates P and P' and, at their outer ends, carry glass beads 15 by which plates Q and Q' are supported while being insulated with respect to plates P and P'. The voltage V Q is applied to plate Q by a conducting lead 20 extending from a button 19 in neck N and the voltage V Q is applied to plate Q' by way of a conducting lead 16 extending between plates Q and Q' and being spaced from plates P and P'.

In order to reduce the necessary length of neck N of the tube envelope, the convergence deflecting means F is located closely adjacent to the main deflection yoke D, and may even axially overlap the location of the latter as shown on FIG. 2. However, when convergence deflecting means F is thus located, it is disposed within the magnetic field with vertical lines of flux produced by main deflecting yoke D for causing the beams to horizontally scan the color screen. Since plate P, bracing members 21, plate P', angle members 12, 13 and electrode G 5 form a closed loop, the magnetic flux changes in such magnetic field of yoke D induces a current to flow in the closed loop, and the induced current, in turn, produces a magnetic field between plates P and P' that acts on the central beam B G in the direction opposed to the horizontal scanning movement of the beams. Since the other beams B R and B B are not acted upon by the magnetic field between plates P and P' resulting from the induced current, at any instant during each horizontal scan the point at which beam B G reaches the aperture grill G P will lag behind the point on the latter at which beams B R and B B converge, whereby misconvergence results.

In accordance with this invention, such misconvergence is avoided or corrected by providing the convergence deflecting plates Q and Q' with different dimensional relationships to the respective shielding plates P and P' so that the electrical fields between plates P and Q and between plates P' and Q', respectively, will have different deflecting effects on beams B B and B R , respectively, and thus cause such beams to reach the aperture grill at the same point as beam B G notwithstanding the fact that beams B R and B B are not subjected, during horizontal scanning, to the magnetic field acting on central beam B G between plates P and P'.

As shown on FIG. 4, the different dimensional relationships of plates Q and Q' with respect to plates P and P' may refer to the distances by which plates Q and Q' are spaced from plates P and P', respectively. Thus, on FIG. 4, the distance d between plates P and Q is larger than the distance d' between plates P' and Q', from which it follows that the flux density or intensity of the electrical field between plates P' and Q', and hence the deflecting force acting on beam B R , will be greater than the flux density or intensity of the electrical field between plates P and Q, and hence the deflecting force acting on beam B B . Thus, the convergence deflection of beam B R will be greater than the convergence deflection of beam B B to cause beams B R and B B to converge at a common point with beam B G at the aperture grill.

As shown on FIG. 5, the mentioned different dimensional relationships of plates Q and Q' with respect to plates P and P' may alternatively refer to the distances along plates P and P' that the plates Q and Q' respectively extend. Thus, on FIG. 5, the plate Q is shown to have a length l in the direction of the tube axis that is smaller than the length l' of the plate Q' in the same direction. In view of the foregoing, beam B B will traverse a distance in passing through the electric field between plates P and Q that is greater than the distance traversed by beam B R in passing through the electric field between plates P' and Q'. Thus, once again the convergence deflection of beam B R will be greater than the convergence deflection of beam B B so as to restore proper convergence of the three beams B R , B G and B B at a common point on the aperture grill.

It is also apparent that the measures according to this invention for correcting the described misconvergence as shown on FIGS. 4 and 5 can be combined, that is, for example, the plate Q may be spaced further from the plate P than the distance of plate Q' from plate P' and the length of plate Q may be made shorter than the length of plate Q'.

Although illustrative embodiments of the invention have been described in detail herein with reference to the drawings, it is to be understood that the invention is not limited to those precise embodiments and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.

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Resisting the tide of post-modernity may be difficult, but I will attempt it anyway.

Your choice.........Live or DIE.That indeed is where your liberty lies.

IMPORTANT NOTE: - FRANK SHARP obsoletetellyemuseum.blogspot.comwas founded as a public free WEB Museum to all kind of people and amateur and professional CRT TELEVISION Lovers who enjoy using and/or preserving - restoring vintage CRT Televisions sets, or only curious public who was unaware of that kind of technolgy of the past. The purpose is to provide information about vintage Television Receivers Publicy on the WEB that is generally difficult to locate; all this as a important milestone general worldwide reference for the future, globally in the public interest.obsoletetellyemuseum.blogspot.com does not provide support or parts for any apparatus on this site nor do we represent any manufacturer listed on this site in any way. Catalogs, manuals and any other literature that is available on this site is made available for a historical record only. Please remember that safety standards have changed over the years and information in old manuals as well as the old Television receivers themselves may not meet modern standards. It is up to the individual user to use good judgment and to safely operate old machinery. The obsoletetellyemuseum.blogspot.com web site will assume NO responsibilities for damages or injuries resulting from information obtained from this site. No offer to sell or license — Nothing in this site/Blog may be interpreted or construed as an offer to sell products that is open for acceptance or the grant, conveyance or implication of any license under any copyrights, patents or other industrial or intellectual property rights.

Many topics are permanent, so may be updated to any material, for add or correct info.

Sure Fun Times, A working TV Discovered with a CRT Oscilloscope !

Safety Hazards:

------------------------------------------------------Safety Hazards in Radio and TV Repair,------------------------------------------------------

People who believe they can conquer nature are clueless that the laws of nature are a precondition of their existence. Their weapon is a miserable idea.When man attempts to rebel against the iron logic of Nature, he comes into struggle with the principles to which he himself owes his existence as a man. And this attack must lead to his own doom.

Anyone attempting to repair any electronic equipment who does not fully understand the shock hazards, as well as the fire hazards associated with working with electronic equipment, should not attempt such procedures! Improperly attempted repair can kill you and burn down your house.Devices that plug into the wall can produce a very lethal electric shock as well cause a fire from incorrect or careless repairs both during servicing or later on.Improper repair of battery operated devices can also result in bad consequences for you, the device, and any equipment attached to it.

Why some people do repairs themselved then? If you can do the repairs yourself, the equation changes dramatically asyour parts costs will be 1/2 to 1/4 of what a professional will chargeand of course your time is free. The educational aspects may also beappealing. You also will learn a lot in the process.

Consumer electronic equipment like TVs, computer monitors, microwave ovens, and electronic flash units, use voltages at power levels that are potentially lethal. Even more so for industrial equipment like lasers and anything else that is either connected to the power line, or uses or generates high voltage.

Normally, these devices are safely enclosed to prevent accidental contact. However, when troubleshooting, testing, making adjustments, and during repair procedures, the cabinet will likely be open and/or safety interlocks may be defeated. Home-built or modified equipment, despite all warnings and recommendations to the contrary - could exist in this state for extended periods of time - or indefinitely.

Depending on overall conditions and your general state of health, there is a wide variation of voltage, current, and total energy levels that can kill.

Microwave ovens in particular are probably THE most dangerous household appliance to service. There is high voltage - up to 5,000 V or more - at high current - more than an amp may be available momentarily. This is an instantly lethal combination.

TVs and monitors may have up to 35 kV on the CRTbut the current isn't low - like a wrong legend saying a "couple of milliamps" but relatively high because of the boost circuit technology and transformer design. However, the CRT capacitance can hold a painful charge for a long time. In addition, portions of the circuitry of TVs and monitors as well as all other devices that plug into the wall socket are line connected.This is actually even more dangerous than the high voltage due to the greater current available - and a few hundred volts can make you just as dead as 35 kV!

Electronic flash units and strobe lights, and pulsed lasers have large energy storage capacitors which alone can deliver a lethal charge - long after the power has been removed. This applies to some extent even to those little disposable pocket cameras with flash which look so innocent being powered from a single 1.5 V AA battery. Don't be fooled - they are designed without any bleeder so the flash can be ready for use without draining the battery!

Even some portions of apparently harmless devices like VCRs and CD players - or vacuum cleaners and toasters - can be hazardous (though the live parts may be insulated or protected - but don't count on it!

This information also applies when working on other high voltage or line connected devices like Tesla Coils, Jacobs Ladders, plasma spheres, gigawatt lasers, hot and cold fusion generators, cyclotrons and other particle accelerators, as well as other popular hobby type projects. :-)

In addition, read the relevant sections of the document for your particular equipment for additional electrical safety considerations as well as non-electrical hazards like microwave radiation or laser light. Only the most common types of equipment are discussed in the safety guidelines, below.

SAFETY guidelines:

These guidelines are to protect you from potentially deadly electrical shock hazards as well as the equipment from accidental damage.

Note that the danger to you is not only in your body providing a conducting path, particularly through your heart. Any involuntary muscle contractions caused by a shock, while perhaps harmless in themselves, may cause collateral damage. There are likely to be many sharp edges and points inside from various things like stamped sheet metal shields and and the cut ends of component leads on the solder side of printed wiring boards in this type of equipment. In addition, the reflex may result in contact with other electrically live parts and further unfortunate consequences.

The purpose of this set of guidelines is not to frighten you but rather to make you aware of the appropriate precautions. Repair of TVs, monitors, microwave ovens, and other consumer and industrial equipment can be both rewarding and economical. Just be sure that it is also safe!

Don't work alone - in the event of an emergency another person's presence may be essential.

Always keep one hand in your pocket when anywhere around a powered line-connected or high voltage system.

Wear rubber bottom shoes or sneakers. An insulated floor is better than metal or bare concrete but this may be outside of your control. A rubber mat should be an acceptable substitute but a carpet, not matter how thick, may not be a particularly good insulator.

Don't wear any jewelry or other articles that could accidentally contact circuitry and conduct current, or get caught in moving parts.

Set up your work area away from possible grounds that you may accidentally contact.

Have a fire extinguisher rated for electrical fires readily accessible in a location that won't get blocked should something burst into flames.

Use a dust mask when cleaning inside electronic equipment and appliances, particularly TVs, monitors, vacuum cleaners, and other dust collectors.

Know your equipment: TVs and monitors may use parts of the metal chassis as ground return yet the chassis may be electrically live with respect to the earth ground of the AC line. Microwave ovens use the chassis as ground return for the high voltage. In addition, do not assume that the chassis is a suitable ground for your test equipment!

If circuit boards need to be removed from their mountings, put insulating material between the boards and anything they may short to. Hold them in place with string or electrical tape. Prop them up with insulation sticks - plastic or wood.

If you need to probe, solder, or otherwise touch circuits with power off, discharge (across) large power supply filter capacitors with a 2 W or greater resistor of 100 to 500 ohms/V approximate value (e.g., for a 200 V capacitor, use a 20K to 100K ohm resistor). Monitor while discharging and/or verify that there is no residual charge with a suitable voltmeter. In a TV or monitor, if you are removing the high voltage connection to the CRT (to replace the flyback transformer for example) first discharge the CRT contact (under the insulating cup at the end of the fat red wire). Use a 1M to 10M ohm 1W or greater wattage resistor on the end of an insulating stick or the probe of a high voltage meter. Discharge to the metal frame which is connected to the outside of the CRT.

For TVs and monitors in particular, there is the additional danger of CRT implosion - take care not to bang the CRT envelope with your tools. An implosion will scatter shards of glass at high velocity in every direction. There is several tons of force attempting to crush the typical CRT. Always wear eye protection. While the actual chance of a violent implosion is relatively small, why take chances? (However, breaking the relatively fragile neck off the CRT WILL be embarrassing at the very least.)

Connect/disconnect any test leads with the equipment unpowered and unplugged. Use clip leads or solder temporary wires to reach cramped locations or difficult to access locations.

If you must probe live, put electrical tape over all but the last 1/16" of the test probes to avoid the possibility of an accidental short which could cause damage to various components. Clip the reference end of the meter or scope to the appropriate ground return so that you need to only probe with one hand.

Perform as many tests as possible with power off and the equipment unplugged. For example, the semiconductors in the power supply section of a TV or monitor can be tested for short circuits with an ohmmeter.

Provide a reliable means of warning that power is applied and that high voltage filter capacitor(s) still hold a charge during servicing. For example, solder a neon indicator lamp (e.g., an NE2 in series with a 100K ohm resistor) across the line input and a super high brightness LEDs in series with 100K, 1 W resistors across the main filter capacitor(s).

Use an isolation transformer if there is any chance of contacting line connected circuits. A Variac(tm) (variable autotransformer) is not an isolation transformer! However, the combination of a Variac and isolation transformer maintains the safety benefits and is a very versatile device. See the document "Repair Briefs, An Introduction", available at this site, for more details.

The use of a GFCI (Ground Fault Circuit Interrupter) protected outlet is a good idea but may not protect you from shock from many points in a line connected TV or monitor, or the high voltage side of a microwave oven, for example. (Note however, that, a GFCI may nuisance trip at power-on or at other random times due to leakage paths (like your scope probe ground) or the highly capacitive or inductive input characteristics of line powered equipment.) A GFCI is also a relatively complex active device which may not be designed for repeated tripping - you are depending on some action to be taken (and bad things happen if it doesn't!) - unlike the passive nature of an isolation transformer. A fuse or circuit breaker is too slow and insensitive to provide any protection for you or in many cases, your equipment. However, these devices may save your scope probe ground wire should you accidentally connect it to a live chassis.

When handling static sensitive components, an anti-static wrist strap is recommended. However, it should be constructed of high resistance materials with a high resistance path between you and the chassis (greater than 100K ohms). Never use metallic conductors as you would then become an excellent path to ground for line current or risk amputating your hand at the wrist when you accidentally contacted that 1000 A welder supply!

Don't attempt repair work when you are tired. Not only will you be more careless, but your primary diagnostic tool - deductive reasoning - will not be operating at full capacity.

Finally, never assume anything without checking it out for yourself! Don't take shortcuts!

Many people who mistakenly feel that ‘old technology’ is somehow more user-friendly, in some strange way automatically good - merely because it is old. Don’t be fooled! Approach old equipment with an open and alert mind and realise that a hot chassis, or a resistor line cord, or asbestos insulation, or selenium rectifiers require much more thought and consideration for safety.

Live chassis are indiscriminate in whom they kill and even if you are a thoughtful, careful kind of person, that doesn’t mean the last person who handled the set was.

Vintage radio and television receivers use 'live chassis' techniques, in which the chassis is connected directly to one side of the incoming mains supply. This means they can be lethal to carry out repair or servicing work on, unless the appropriate safety measures are in place.

Another thing about live-chassis sets - live spindles. We’ve touched on this already but it’s worth making the point once more. The shafts of switches and potentiometers fixed to the chassis may well be at chassis potential and thus live. The bakelite or wood cabinet is insulated but these shafts are not, and if someone lost the proper grub screw and replaced a knob using a cheesehead screw, the next person to grip that knob may get a dose of 250 volts. Originally these grub screws were sealed and embedded in wax but you cannot rely on subsequent tinkerers having the same high standards.

Even in more orthodox apparatus standards of insulation were not always as high as they are now. Soldered connections to HT and mains wiring should always have rubber or plastic sleeving but in times gone by this was often omitted (or it may since have perished). Beware too of kinked and frayed braiding on cloth-covered mains cords, particularly when the cord has a dropper conductor.

If you are not satisfied that you fully understand the risks involved in this sort of work, do not proceed any further. Instead seek advice and assistance from a competent technician or engineer.

Whenever you acquire a new treasure there's always a terrific temptation to try it out. With mains-driven equipment that means plugging it in and seeing if it works. Well don't, not until you have made some quick checks.

Before contemplating connecting any unknown receiver to the mains supply, spend a little time inspecting it for signs of missing or loose parts, blown fuses, overheating or even fire damage. Use a meter to check obvious points to ensure no short circuit exists (e.g. across the mains input). If you then decide to apply power keep clear but be observant since an elderly electrolytic might explode! This can be avoided if you can apply power gradually through a variac. Auto-transformers are handy for supplying reduced power to sets being repaired but they are not a substitute for a proper isolation transformer!

If you are working with electricity and your work area has a concrete floor, a rubber mat is essential, particularly during damp weather! Where possible try to arrange a neat working area away from water or central heating pipes. For safety try to arrange that this area is separate from the area occupied by your family. This is emphasised because inadvertently rushing to answer a telephone you might just leave a TV chassis connected to a supply and curious little fingers know nothing of the dangers of electricity - or, for that matter - the lethal vacuum encased within every picture tube!

Many younger enthusiasts may not be aware of the dangers of mishandling tubes, in particular the old round types found in early TVs. When handling these tubes eye protection should be worn and tubes must not be left lying around, they must be stored in boxes. The glass is surprising fragile and can implode without any provocation or warning. Bits of glass flying around at high speed can be deadly. The notes following are inspired by Malcolm Burrell again.

Picture tubes are perhaps one of the most hazardous items in any TV receiver. This is because most are of glass construction and contain a very high vacuum. If you measured the total area of glass in any picture tube then estimated the pressure of air upon it at 14.7lb. per square inch, you would discover that the total pressure upon the device could amount to several tons! Fracturing the glass suddenly would result in an extremely rapid implosion such that fragments of glass, metal and toxic chemicals would be scattered over a wide area, probably causing injury to anyone in close proximity. In modern workshops it is now a rule that protective goggles are worn when handling picture tubes.

The weakest point in most picture tubes is where the thin glass neck containing the electron gun is joined to the bowl. It is therefore essential that you refrain from handling the tube by its neck alone. Once a tube is removed from the receiver hold it vertically with the neck uppermost and one hand beneath the screen with the other steadying the device by the neck.With larger devices it is sometimes easier to grip the peripheral of the screen with both hands.

Until the advent of reinforced picture tubes, most were mounted in the cabinet or on the TV chassis by some form of metal band clamped around the face.Never support the weight of the tube by this band since it has been known for the tube to slide out! Some of the larger tubes are extremely heavy. It may, therefore, be easier to enlist assistance.

Before starting to remove a tube, first discharge the final anode connection to the chassis metalwork and preferably connect a shorting lead to this connection whilst you are working. It might be convenient to keep a spare piece of EHT cable with a crocodile clip at one end and a final anode connector at the other.

Exercise care when removing picture tubes from elderly equipment. You may find that the deflection coils have become stuck to the neck. It is extremely dangerous to use a screwdriver prise them away. Gently heating with a hairdryer or soaking in methylated spirit is safer.

Disposal of picture tubes also requires care. Unless rendered safe they should never be placed in dustbins or skips. Many engineers swipe the necks off tubes in cavalier fashion using a broom handle but this is not recommended. A safer method is to make a hole in the side of a stout carton, preferably one designed to hold a picture tube. The tube is placed in the carton and the neck broken using a broom handle. The carton should then be clearly labelled that it contains chemicals and broken glass!

Therefore people who believe they can conquer nature are clueless that the laws of nature are a precondition of their existence. Their weapon is a miserable idea.When man attempts to rebel against the iron logic of Nature, he comes into struggle with the principles to which he himself owes his existence as a man. And this attack must lead to his own doom.

Think for yourself. Otherwise you have to believe what other people tell you.

For most people thinking is a matter of fortune.A society based on individualism is an oxymoron.Freedom is at first the freedom to starve.A wise fool speaks, because he has something to say.A fool speaks, because he has to say something.A wise fool is silent, because there is nothing to say.A fool is silent, because he has nothing to say.

Resist or regretWork for what's good for our people

Help stem the dark tideStand tall or be beat downFight back or die

The man who does not exercise the first law of nature—that of self preservation — is not worthy of living and breathing the breath of life.

We now live in a nation where doctors destroy health, lawyers destroy justice, universities destroy knowledge, governments destroy freedom, the press destroys information, religion destroys morals and our banks destroy the economy.The globalist argument is that if only we erase distinctions, obliterate identities, put everyone on a level playing field, etc.. we can eliminate war and everyone can be so prosperous and efficient, such great cogs in a well-oiled global machine.There will be no more historical grievances because people will no longer even care, they'll have no connection to the past, no foolish pride in past accomplishments of people totally unrelated to them.A globalized culture, no borders, everyone a citizen of the world.Know this: I will never acquiesce to this corrupt, inhuman, Borg-like vision. The dangerous lunatics who push us towards their globalized "utopia" are my enemy. How exactly all this will play out, whether through wars, or whether we can thwart the globalist agenda peacefully (this is my hope of course) I don't know. But I do know that unless people are willing to fight and die, globalism will win out in the end.The actual crimes committed by the EU against the European peoples are directly in violation of the 1948 UN genocide convention, Article II: (c) Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part; (d) Imposing measures intended to prevent births within the group; (e) Forcibly transferring children of the group to another group.* The man who does not exercise the first law of nature—that of self preservation — is not worthy of living and breathing the breath of life.

TELEVISION HISTORY IN BRIEF

Television history

At 1928 Baird transmits from London to New York, using his mechanical system.with 30 vertical lines. By 1930 it was clear that mechanical television systems could never produce the picture quality required for commercial success. For this reason mechanical system was rapidly succeeded by the electronic TV systems. The first all-electronic American systems in 1932 used only 120 scanning lines at 24 frames per second Since the mid-1930s picture repetition frequency (field rate or frame rate) has been the same as the mains frequency, either 50 or 60Hz according to the frequency used in each country. This is for two very good reasons. Studio lighting generally uses alternating current lamps and if these were not synchronised with the field frequency, an unwelcome strobe effect could appear on TV pictures. Secondly, in days gone by, the smoothing of power supply circuits in TV receivers was not as good as it is today and ripple superimposed on the DC could cause visual interference. If the picture was locked to the mains frequency, this interference would at least be static on the screen and thus less obtrusive.To determine what electronic system to use, the BBC sponsored trial broadcasts by two systems, one by Baird, with 240 lines, and one by EMI with 405 lines. Scheduled electronic television broadcasting began in England in 1936 using 405-line system (lasted until the 1980s in the UK). Germany made their forst TV broadcasts at 1936 olympics using 180-line TV system. Germany also made their TV broadcasts by the fall of 1937 using a 441-line system. Also fFrance tested TV (455 line system). RCA introduced electronic television to the U. S. at the 1939 World's Fair,and began regularly scheduled broadcasting at the same time (525 line system).In 1940 the USA established its 525-line standard. At year 1941 the 525-line standard, still in use today in USA, was adopted.Russia also produced TV sets before the war (240 and 343 line systems).World War Two interrupted the development of television. Immediately after World War Two production of TV sets started in the U.S-In USA there was TV broadcasts and few throusand receivers at 1945. In the early 1950s, two competing color TV systems emerged: CBS sequential color (used color wheel) and RCA dot sequential system. At 1953 color broadcasting officially arrives in the U.S. on Dec. 17, when FCC approves modified version of an RCA system.It calls this new RCA color system "NTSC" color. The first NTSC color TVs were on the marker at 1954.In Europe the TV broadcasts started to use experiment using 625 line system 1950s. This standard is used nowadays throughout Europe. France also tried 819 line system at the same time (this system was in use to 1980s). The rest of Europe opted for 625 lines, a system devised in 1946 by two German engineers, M??ller and Urtel (it appears that the Russians came up independently with a very similar system). The use of PAL color standard started at around 1967 and is still in use. The SECAM color system (used in France) testing started also at 1967. The TV broadcasting history has not ended. The newst thign is digital television. It is expected that terrestrial television will open up billion-dollar opportunities for those companies and organisations best prepared to embrace this new broadcasting era. At 1996 small digital satellite dishes hit the market. They become the biggest selling electronic item in history next to the VCR.

Using TV 24H

TV has something for everyone. Idiots, intellectuals, fans of all sorts. Some people are couch potatoes, watch anything just to sit there and be mindless. That's their problem. Children have always needed to be monitored by their parents. If people gotta a mind for it they could figure out the real news even without the internet and there has always been a library.

Is TV bad in and of itself? The researchers aren’t saying that. But we all know that watching television is a solitary, isolating occupation that keeps you sedentary. Sitting in front of the boob tube reduces the time you have available to exercise, interact with your family, read books, and be outdoors. This new research dovetails with other studies, which have linked excessive TV time to obesity and higher rates of cardiovascular disease.

watching too much television can jeopardize your whole family’s health.

This should be a wake-up call to all adults. Stay active. Go outside. Spend time with your spouse and your children with the television off. Read a book and do crossword puzzles to stimulate your imagination and your brain. Reduce your screen time as much as you can.

The National Cancer Institute researchers suggest that watching TV is a public health issue. The price we are paying for our technology-driven lives may be much higher than we previously realized !

DON'T WATCH TV AT ALL !!

The Propaganda TV Machine a.k.a. The Ministry of Truth delivers The Truth from The Government to the people.

At least, that's what they say. In fact, a Propaganda Machine is only employed by The Empire and used to brainwash people into Gullible Lemmings who believe that everything is all right when in fact, it isn't, and that the very people who could help them are their enemies.

Girl Looking TV.

Happy Times:

Do you remember when a telly looked like a real telly? When it was a piece of furniture that you lavished love on, even polished from time to time ?When it was a piece of somewhat at looking in to ?When it was a piece of Highest tech looking inside ? First, this site is a Digital free, HD free, flat panel, HDMI, China, Turks, Afrika free zone. All in all a wealth of vintage information at your finger tips, a one stop unique experience. So step on in, leave the modern throw-away world behind, travel back in time to a vintage world of repair and enjoy.This site has stirred memories about the watching TV's days on a CRT TUBE television......Childhood memories, your parents getting their first colour tv, a b/w or color portable, perhaps memories of renting or buying your first set remote featured, perhaps your days working in the trade, selling or repairing them....... If you enjoyed this site, found its content left you all misty eyed then just talk about it as it would be very welcome............like the time to recover and restore a set ................and happy reminiscing.

Digital TV in Brief.

Digital TV:

Digital television is a hot topic now.If you have looked at television sets at any of the big electronics retailers lately, you know that Digital TV, or DTV, is a BIG deal right now in the U.S. In Europe Digital TV is also a hot topic, because many countries have started terrestrial digital TV broadcasts and plan to end analogue broadcasts after some years (will take 5-10 years). Satellite TV broadcasts have also shifted very much to digital broadcasts.The main advantage if digital broadcasts are that it does not havethe picture quality problems of analogue TVs (it had it's own videoproblems caused by video compression), it allowes putting more TV channels to same medium (TV channel frequencies and satellites) and it allows new services (like HDTV and interactive multimedia). The digital brodcasts are generally designed to use such modulation that the digital data stream (typically around 20-30 Mbit/s) is modulated to the same bandwidth (around 6 MHz) as the analogue TV broadcasts. The used modulation vary between different media, which means thatdifferent modulation techniques are used in terrestrial transmissions, cable TV and satellite. Different modulations are used because of the different characteristics of those transmission medias. There is not on "digital TV", but several different variations of it in use.The basic technology of digital TV, known as MPEG 2 video compressionand MPEG 2 transmission stream format, is same around the world, butis is used somewhat differently in different standards used in differentcountries.

USA uses ACTS Digital Televisio Standard, which standardizes NTSC format transmissions, HDTV transmission, sound formats and data signal modulation in use. The ATSC MPEG-2 formats for DTV, including HDTV, uses 4:2:0 samling for video signal. The US system uses a fixed power and a fixed maximum bitrate, at which some bits are always transmitted. That rate is typically 19.3 Mb/sec.

Europe uses DVB (Digital Video Broadcasting) standard. This standardallows basically normal PAL resolution transmisssion (vasically HDTVcould be added later but is not yet standardized) with several audio formats, digital data rates and digital signal modulation. There are several different variations fo DVB standard for different media:

DVB-T for terrestrial broadcastsDVB-S for satelliteDVB-C for cable TV

Those different DVB versions varyon the data signal modulation methods, error correction and frequency bands used. DVB and option for some interactive extra services, but thestandardization of this is not ready here yet(there are fire different incompatible interactive servicessystems in use in different countries and by different broadcasters).

The process of transmitting digital TV signal is the following: Analog video/audio - digitisation - MPEG compression - Multiplexing ( youcan now call it digital) - Preparation for transmisson - modulation toanalog carrier.Reception process is the following: Demodulation of analogue carrier - Error correction - Demultiplexing - MPEG decompression - DA conversion to get analogue signal (unless you use digital display). The analoguie video signal that gets digitized can be practically from any video source, for example produced with old analogue video production equipment and distributed with a video tape. In high-end system the information is analogue only in the image sensor on the video camera, and from this on the signal gets digitally processed. In many real-life TV production systems the reality is something between those two extremes.

At least in Europe, the signal level requirements for DVB-T are well below the analog requirements, so the transmitter power is much less than on the analog side. In the NorDig recommendation the minimum received signal level for 64QAM, 7/8 code rate with a Rayleigh fading path and 8 dB receiver noise figure would be -64 dBm. With other code rates, modulations and fading mechanisms, the requirement is lower. Many receivers can perform much better at conditions where there is no fading (a quasi error free less than one uncorrected error/hour signal even at 27 dBuV (-82 dBm) with 64QAM and 8 MHz channel width). For analog signals, the recommended level is more than 1 mV (+60 dBuV, -49 dBm). While the ERP can be at least 10 dB lower than analog, the question of power consumption is more complicated, since COFDM with 64QAM carriers require a quite good linearity, which may affect the efficiency and hence power consumption.

Digital TV system in use in USA

The FCC mandate to change our broadcast standards from NTSC analog to ATSC digital broadcasting (DTV) is big bold move, requiring changes in everything from the way the studios shoot video, the format that's transmitted, to the equipment we use to receive and watch broadcastsDTV (digital TV) applies to digital broadcasts in general and to the U.S. ATSC standard in specific. The ATSC standard includes both standard-definition (SD) and high-definition (HD) digital formats. The notation H/DTV is often used to specifically refer to high-definition digital TV. The federal mandate grants the public airwaves to the broadcasters to transmit digital TV in exchange for return of the current analog NTSC spectrum, allowing for a transition period in the interim. At the end of this period scheduled for 2006, broadcasters must be fully converted to the 8VSB broadcast standard. Digital Television ("DTV") is a new broadcast technology that will transform television. The technology of DTV will allows TV broadcasts with movie-quality picture and CD- quality sound and a variety of other enhancements (for example data delivery). With digital television, broadcasters will be able to offer free television of higher resolution and better picture quality than now exists under the current mode of TV transmission. If broadcasters so choose, they can offer what has been called "high definition television" or HDTV, television with theater-quality pictures and CD-quality sound. . Alternatively, a broadcaster can offer several different TV programs at the same time, with pictures and sound quality better than is generally available today. HDTV (high-definition TV) encompasses both analog and digital televisions that have a 16:9 aspect ratio and approximately 5 times the resolution of standard TV (double vertical, double horizontal, wider aspect). High definition is generally defined as any video signal that is at least twice the quality of the current 480i (interlaced) analog broadcast signal. There are 18 approved formats for digital TV broadcasts, but only two (720p/1080i) are proper definition of the term HDTV. The advent of high definition has allowed monitors to read images differently, either in standard interlaced format or progressively. Sets that do not have any decoding capabilities but can display the high-resolution image is often labeled as "HD-Ready" a term that describes 80% or more of the Digital TVs on the market. HDTV displays support digital connections such as HDMI (DVI) and IEEE 1394/FireWire, although standardization is not finished. HDTV in the US is part of the ATSC DTV format. The resolution and frame rates of DTV in the US generally correspond to the ATSC recommendations for SD (640x480 and 704x480 at 24p, 30p, 60p, 60i) and HD (1280x720 at 24p, 20p, and 60p; 1920x1080 at 24p, 30p and 60i). In addition, a broadcaster will be able to simultaneously transmit a variety of other information through a data bitstream to both enhance its TV programs and to provide entirely new services. The technical specifications of USA DTV system is defined in ACTS Digital Television Standards.

Digital TV in Europe

Digital TV brodacasting in Europe is done according to DVB standards. DVB technology has become an integral part of global broadcasting, setting the global standard for satellite, cable and terrestrial transmissions and equipment. There are three versions of DVB in use: DVB-S, DVB-C and DVB-T.DVB-T is a flexible system allowing terrestrial broadcastersto choose from a variety of options to suit their various service environments. This allows the choice between fixed roof-top antenna, portableand even mobile reception of DVB-T services. Broadly speaking the trade-off in one of service bit-rate versus signal robustness.

DVB-T network is very flexible. Having many transmitters all on the same frequency is not a problem for the used COFDM based system. COFDM has been chosen and designed to minimise the effects of multipath in obstructed reception areas. In fact multipath signals can significantly improve the overall received signal with no adverse effects. These properties are particularly valuable for radio cameras and mobile links. DVB-T because of its unique design which allows single frequency networks (SFN). This means that many transmitters along the planned routes can transmit on the same frequency. It is also possible to use simple gap fillers that amplify and retransmit the signal. In-air digital TV broadcasts in Europe use DVB-T. 8 MHz of bandwidth may be used to provide a 24 Mbps digital transmission path using Coded Orthogonal Frequency Division Multiplexing (COFDM) modulation (theoretical maximum 31.67 Mbits for 8 MHz bandwidth). In cases where less bandwidth is available (6 or 7 MHz), the data rate is somewhat lower (around 20 Mbit/s).

DVB-C does the same function as DVB-T, but the modulation used in this system is optimized to operate well in cable TV networks. The modulation used in DVB-C is QAM. Systems from 16-QAM up to 256-QAM can be used, but the system centres on 64-QAM, in which an 8MHz channel can accommodate a physical payload of about 38 Mbit/s. Digital cable TV in Europe uses DVB-C. The DVB standard for the cable return path has been developed jointly with DAVIC, the Digital Audio Visual Council. The specification uses Quadrature Phase Shift Keying (QPSK) modulation in a 200kHz, 1MHz or 2MHz channel to provide a return path for interactive services (from the user to the service provider) of up to about 3Mbit/s. The path to the user may be either in-band (embedded in the MPEG-2 Transport Stream in the DVB-C channel) or out-of-band (on a separate 1 or 2MHz frequency band).

DVB-S is the satellite version of DVB. Satellite transmission has lead the way in delivering digital TV to viewers. Established in 1995, the satellite standard DVB-S is the oldest DVB standard, used on all six major continents. QPSK modulation system is used, with channel coding optimised to the error characteristics of the channel. A typical satellite channel has 36 MHz bandwidth, which may support transmission at up to 38 Mbps (assuming delivery to a 0.5m receiving antenna) using Quadrature Phase Shift Keying (QPSK) modulation. 16 bytes of Reed Solomon (RS) coding are added to each 188 byte transport packet to provide Forward Error Correction (FEC) using a RS(204,188,8) code. For the satellite transmission, the resultant bit stream is then interleaved and convolutional coding is applied.

The core of the DVB digital data stream isthe standard MPEG-2 "data container",which holds the broadcast and service information.This flexible "carry-all" can containanything that can be digitised, includingmultimedia data. The MPEG-2 standards define how to format the various component parts of a multimedia programme (which may consist of: MPEG-2 compressed video, compressed audio, control data and/or user data). It also defines how these components are combined into a single synchronous transmission bit stream. The process of combining the steams is known as multiplexing. The multiplexed stream may be transmitted over a variety of links, standards / products.Each MPEG-2 MPTS multiplex carries a number of streams which in combination deliver the required services. A typical data rate of such multiplex is around 24 Mbps for terrestrial brodcasts.

European DVB systems currently transmit only standard definition TV signals and set top boxes also handle only normal TV resolution. It would be possible to transmit HDTV signals on DVB data stream, but those broadcasts have not yet started in any wide scale. There is one satellite broadcater that broadcasts HDTV DVB signals in Europe (some cable TV operators carry that signal on their cable).

Many DVB-T integrated TV sets, and some set top boxes, in the Europe come with a Common Interface slot - which is pretty much the same form-factor as a PC Card (aka PCMCIA) used in PC laptops. This CI slot accepts a Conditional Access Module, in the same way that DVB-S receivers do, which implements at least one (some can do more than one) decryption algorithm. This CAM may also, itself, have a smart card slot to accept a consumer subscription card to authorise decryption - you plug your smartcard into your CAM and your CAM into the CI slot in your receiver/IDTV. Some DVB receivers have an integrated CAM (in the case of some receivers this is implemented purely in software, with no extra hardware required) rather than a CI slot to plug in a 3rd party device. With these type of receivers you just plug in the smart card and don't have to worry about CI slots and buying CAMs. So there is an interface standard for DVB - but different broadcasters can chose different encryption schemes, requiring different CAMs for decryption.

DVB Standards and related documents are published by the European Telecommunications Standards Institute (ETSI). These include a large number of standards and technical notes to complement the MPEG-2 standards defined by the ISO.

There are few different standard how interactive TV functionaly is implemented in DVB-systems in use in differenct countries. DVB-MHP is one gaining some acceptance. Multimedia Home Platform (MHP) is the open middleware system designed by the DVB Project (www.dvb.org).